A364560 Numbers k for which A156552(k) < k.

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 21, 24, 25, 27, 30, 32, 35, 36, 40, 42, 45, 48, 49, 50, 54, 55, 60, 63, 64, 70, 72, 75, 77, 80, 81, 84, 90, 91, 96, 98, 99, 100, 105, 108, 110, 120, 121, 125, 126, 128, 135, 140, 143, 144, 147, 150, 154, 160, 162, 165, 168, 169, 175, 180, 182, 187, 189, 192, 195, 196

Offset: 1

Author

Antti Karttunen, Jul 28 2023

Keywords

• nonn

Comments

Numbers k such that A005941(k) <= k.

Sequence A005940(A364542(.)) sorted into ascending order.

If k is a term, then also 2*k is present in this sequence, and vice versa.

Crossrefs

Positions of nonpositive terms in A364559.

Cf. A005941, A156552, A364542, A364562 (complement).

Subsequences: A029747, A364550, A364561 (odd terms).

Programs

PARI

A156552(n) = { my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
isA364560(n) = (A156552(n) < n);