A060781 a(n) = lcm(sigma(n+1), sigma(n)), where sigma = A000203.

3, 12, 28, 42, 12, 24, 120, 195, 234, 36, 84, 28, 168, 24, 744, 558, 234, 780, 420, 672, 288, 72, 120, 1860, 1302, 840, 280, 840, 360, 288, 2016, 1008, 432, 432, 4368, 3458, 1140, 840, 2520, 630, 672, 1056, 924, 1092, 936, 144, 1488, 7068, 1767, 2232, 3528

Offset: 1

Author

Labos Elemer, Apr 26 2001

Keywords

• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000
• Index entries for sequences related to sigma(n).

Crossrefs

Cf. A000203.

Programs

Mathematica

LCM @@@ Partition[DivisorSigma[1, Range[50]], 2, 1] (* Amiram Eldar, Mar 25 2024 *)

PARI

a(n) = { lcm(sigma(n), sigma(n+1)) } \\ Harry J. Smith, Jul 11 2009

Formula

a(n) = lcm(A000203(n+1), A000203(n)).

Extensions

Name corrected by Amiram Eldar, Mar 25 2024