A335662 Numbers k such that A335660(k) = 2.

9, 13, 14, 15, 19, 20, 21, 44, 45, 74, 75, 109, 110, 111, 200, 201, 284, 285, 620, 621, 830, 831, 1304, 1305, 1490, 1491, 1879, 1880, 1881, 2090, 2091, 2144, 2145, 2690, 2691, 2804, 2805, 3469, 3470, 3471, 5420, 5421, 5659, 5660, 5661, 9440, 9441, 11834, 11835

Offset

1,1

Links

Table of n, a(n) for n=1..49.

Altug Alkan, Andrew R. Booker, and Florian Luca, On a recursively defined sequence involving the prime counting function, arXiv:2006.08013 [math.NT], 2020.

Mathematica

f[1] = 1; f[n_] := f[n] = PrimePi[n] - PrimePi[Sum[f[k], {k, 1, n - 1}]]; m = 12000 ; Position[Range[m] - Accumulate @ Array[f, m], 2] // Flatten (* Amiram Eldar, May 03 2021 *)

Crossrefs

Cf. A000720, A334714, A335294, A335660.

Sequence in context: A193995 A070607 A340490 * A191891 A135439 A176188

Adjacent sequences: A335659 A335660 A335661 * A335663 A335664 A335665

Keyword

nonn

Author

Seiichi Manyama, Jun 17 2020

Status

approved