A162967 Values taken by the sigma(sigma(n)) function A051027, with repetition, sorted into ascending order.

1, 4, 7, 8, 12, 14, 15, 24, 24, 28, 28, 32, 32, 39, 39, 42, 56, 56, 60, 60, 60, 60, 63, 63, 72, 80, 84, 90, 91, 96, 96, 96, 96, 104, 112, 114, 120, 120, 120, 120, 124, 124, 124, 126, 128, 128, 133, 160, 168, 168, 168, 168, 171, 171, 186, 186, 195, 195, 195, 195, 195

Offset: 1

Author

Jaroslav Krizek, Jul 19 2009

Keywords

• nonn

Comments

Removal of duplicates generates A070286. - R. J. Mathar, Jul 21 2009

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).

Crossrefs

Cf. A007609, A002191. - R. J. Mathar, Jul 21 2009

Cf. A051027, A070286.

Programs

PARI

f(k) = {my(v = invsigma(k), c = 0); for(i = 1, #v, c += invsigmaNum(v[i])); c;} \\ using Max Alekseyev's invphi.gp
list(lim) = {my(m); for(k = 1, lim, m = f(k); for(i = 1, m, print1(k, ", ")));} \\ Amiram Eldar, Dec 26 2024