A360117 Numbers k such that for all their prime factors p, v(p-1) <= v(k-1), where v(n) = A007814(n) is the 2-adic valuation of n.

2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 21, 23, 25, 27, 29, 31, 32, 33, 37, 41, 43, 45, 47, 49, 53, 57, 59, 61, 63, 64, 65, 67, 69, 71, 73, 77, 79, 81, 83, 89, 93, 97, 99, 101, 103, 105, 107, 109, 113, 117, 121, 125, 127, 128, 129, 131, 133, 137, 139, 141, 145, 147, 149, 151, 157, 161, 163, 165, 167

Offset

1,1

Links

Table of n, a(n) for n=1..71.

Mathematica

q[n_] := Module[{v = IntegerExponent[n - 1, 2]}, AllTrue[FactorInteger[n][[;; , 1]], IntegerExponent[# - 1, 2] <= v &]]; Select[Range[2, 200], q] (* Amiram Eldar, Feb 10 2023 *)

Prog

(PARI) isA360117(n) = A360116(n);

Crossrefs

Union of A000040, A000079 \ {1} and A345330 (odd composite terms).

Cf. A007814, A360116 (characteristic function).

Sequence in context: A344979 A273130 A273200 * A014567 A324769 A328867

Adjacent sequences: A360114 A360115 A360116 * A360118 A360119 A360120

Keyword

nonn

Author

Antti Karttunen, Feb 10 2023

Status

approved