This isn't 100% accurate (Rainbow Falls is NOT 43 ) But it was really close so I thought I'd share it

Rank Episode

1 Rarity Takes Manehattan

2 Sweet and Elite

3 Suited for Success

4 Magic Duel

5 Sisterhooves Social

6 Inspiration Manifestation

7 A Dog and Pony Show

8 Simple Ways

9 Look Before You Sleep

10 For Whom the Sweetie Belle Toils

11 Power Ponies

12 The Best Night Ever

13 Maud Pie

14 Boast Busters

15 Filli Vanilli

16 Owl's Well That Ends Well

17 Green Isn't Your Color

18 Secret of My Excess

19 Castle Mane-ia

20 The Crystal Empire

21 The Mysterious Mare Do Well

22 Dragon Quest

23 Dragonshy

24 Family Appreciation Day

25 A Friend in Deed

26 Bats!

27 Stare Master

28 Apple Family Reunion

29 Equestria Girls - Movie

30 Over a Barrel

31 The Return of Harmony

32 Somepony to Watch Over Me

33 A Canterlot Wedding

34 Three's a Crowd

35 May the Best Pet Win!

36 Applebuck Season

37 Twilight Time

38 Hurricane Fluttershy

39 Testing Testing 1, 2, 3

40 Call of the Cutie

41 Leap of Faith

42 Fall Weather Friends

43 Pinkie Apple Pie

43 Rainbow Falls

45 Hearth's Warming Eve

46 The Super Speedy Cider Squeezy 6000

47 Keep Calm and Flutter On

48 A Bird in the Hoof

49 Bridle Gossip

50 It's About Time

51 Equestria Games

52 The Cutie Mark Chronicles

52 The Cutie Pox

54 Lesson Zero

55 Swarm of the Century

56 Twilight's Kingdom

57 One Bad Apple

58 The Ticket Master

59 Pinkie Pride

60 Trade Ya!

61 Daring Don't

62 Baby Cakes

63 The Show Stoppers

64 Princess Twilight Sparkle

65 Ponyville Confidential

65 MMMystery on the Friendship Express

67 Hearts and Hooves Day

68 Games Ponies Play

69 The Last Roundup

70 Winter Wrap Up

71 Magical Mystery Cure

72 Too Many Pinkie Pies

73 Feeling Pinkie Keen

73 Party of One

75 Putting Your Hoof Down

76 Luna Eclipsed

77 Read It and Weep

78 Griffon the Brush-Off

79 Friendship is Magic

80 Just For Sidekicks

81 Wonderbolts Academy

82 Spike at Your Service

83 Flight to the Finish

84 It Ain't Easy Being Breezies

85 Sleepless in Ponyville

86 Sonic Rainboom