A206421 Corresponding values of sigma(m) of numbers in A206036.

12, 18, 12, 24, 24, 31, 18, 42, 32, 24, 60, 31, 42, 56, 72, 32, 48, 54, 48, 60, 56, 90, 42, 96, 84, 72, 48, 124, 72, 98, 54, 120, 72, 120, 80, 90, 60, 168, 96, 104, 84, 144, 126, 96, 144, 72, 114, 124, 140, 96, 168, 80, 186, 126, 84, 224, 108, 132, 120, 180

Offset: 1

Author

Jaroslav Krizek, Feb 07 2012

Keywords

• nonn

Examples

			a(1) = 12 because sigma(A206036(1)) = sigma(6) = 12.
		

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. A000203, A159886 (values k such that sigma(x)= k has more than one solution), A206036 (numbers m such that sigma(m) = sigma(k) has solution for distinct k).

Programs

PARI

list(lim) = my(s); for(k = 1, lim, s = sigma(k); if(invsigmaNum(s) > 1, print1(s, ", "))); \\ Amiram Eldar, Dec 15 2024, using Max Alekseyev's invphi.gp

Formula

a(n) = A000203(A206036(n)). - Amiram Eldar, Dec 15 2024