A272329 Indices of records in A272328.

1, 3, 16, 15, 35, 39, 45, 91, 111, 117, 135, 364, 287, 296, 292, 273, 369, 385, 429, 482, 465, 866, 819, 861, 915, 964, 1154, 1209, 1281, 1558, 1448, 1395, 1845, 1928, 2432, 2336, 2308, 2306, 2275, 2379, 3472, 3416, 3285, 3344, 2583, 3224, 2715, 2775, 2896, 3003

Offset: 1

Author

Tom Edgar, Apr 25 2016

Keywords

• nonn

Crossrefs

Cf. A272328, A081375.

Programs

Mathematica

t = Table[Count[Range@ n, k_ /; EulerPhi@ n == EulerPhi[n + k]], {n, 3600}]; TakeWhile[Flatten[FirstPosition[t, #] & /@ Range@ Max@ t] /. n_ /; MissingQ@ n -> 0, # != 0 &] (* Michael De Vlieger, Apr 25 2016, Version 10.2 *)

Sage

L=[sum([1 for k in [1..n] if euler_phi(n)==euler_phi(n+k)]) for n in [1..4000]]
print([L.index(i)+1 for i in [1..50]])