OFFSET
1,1
LINKS
PROG
(PARI)
A156552(n) = {my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552 by David A. Corneth
isA324726(n) = ((2*n)==bitor(2*n, sigma(n)));
isA324723(n) = if(n>1, isA324726(A156552(n)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Mar 15 2019
STATUS
approved