A057921 d(n+1) divides d(n), where d(n) is number of positive divisors of n.

2, 6, 10, 12, 14, 18, 21, 22, 26, 28, 30, 33, 34, 38, 40, 42, 44, 46, 52, 54, 56, 57, 58, 60, 66, 70, 72, 75, 78, 80, 82, 84, 85, 86, 88, 90, 93, 94, 96, 98, 102, 104, 105, 106, 108, 110, 112, 114, 116, 118, 122, 126, 128, 130, 132, 133, 135, 136, 138, 140, 141, 142

Offset

0,1

Links

Ivan Neretin, Table of n, a(n) for n = 0..10000

Example

10 is included because d(11) = 2 divides d(10) = 4.

Mathematica

Select[Range@150, Divisible @@ DivisorSigma[0, {#, # + 1}] &] (* Ivan Neretin, May 29 2015 *)

Crossrefs

Cf. A057922, A005237.

Sequence in context: A305634 A139710 A194712 * A095300 A097381 A264964

Adjacent sequences: A057918 A057919 A057920 * A057922 A057923 A057924

Keyword

nonn

Author

Leroy Quet, Nov 11 2000

Status

approved