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A336462
Numbers k for which A335915(sigma(k)) = A335915(sigma(sigma(k))).
5
1, 2, 5, 12, 19, 24, 27, 28, 38, 39, 44, 54, 56, 59, 60, 65, 78, 83, 84, 87, 92, 95, 123, 124, 129, 133, 136, 143, 160, 167, 168, 178, 212, 223, 248, 258, 259, 266, 269, 276, 285, 288, 297, 308, 360, 393, 395, 413, 427, 429, 437, 446, 455, 473, 479, 501, 518, 522, 528, 555, 560, 581, 611, 612, 681, 738, 752, 755
OFFSET
1,2
COMMENTS
Numbers k for which A336455(k) = A336455(sigma(k)) = A336456(k).
Numbers k such that sigma(k) is in A336461.
See comments in A336464.
PROG
(PARI)
A000265(n) = (n>>valuation(n, 2));
A335915(n) = { my(f=factor(n)); prod(k=1, #f~, if(2==f[k, 1], 1, (A000265((f[k, 1]^2)-1)^f[k, 2]))); };
isA336462(n) = (A335915(sigma(n))==A335915(sigma(sigma(n))));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 22 2020
STATUS
approved