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A336561
Numbers k at which point A336459(k) appears multiplicative, but A051027(k) does not.
5
506, 1819, 2024, 2714, 3674, 3818, 4554, 5088, 5750, 5786, 6026, 6762, 6842, 7215, 7276, 9487, 9523, 10442, 11895, 12397, 12650, 13178, 13303, 14235, 14696, 15272, 15962, 16346, 16371, 18216, 18458, 19274, 19514, 19690, 19706, 20179, 20378, 21079, 21255, 21626, 22066, 22586, 22682, 23000, 23144, 23322, 24104, 24246
OFFSET
1,1
EXAMPLE
506 = 2*11*23 is a term as A336459(2)*A336459(11)*A336459(23) = 1*7*5 = 35 = A336459(506), while A051027(2)*A051027(11)*A051027(23) = 4*28*60 = 6720 <> A051027(506) = 2520. Note that 2520 = 2^3 * 3^2 * 5 * 7, thus A065330(2520) = 5*7 = 35.
PROG
(PARI)
is_fun_mult_on_n(fun, n) = { my(f=factor(n)); prod(k=1, #f~, fun(f[k, 1]^f[k, 2]))==fun(n); };
A051027(n) = sigma(sigma(n));
A336546(n) = is_fun_mult_on_n(A051027, n);
A065330(n) = (n>>valuation(n, 2)/3^valuation(n, 3));
isA336561(n) = (A336546(n)<is_fun_mult_on_n(A336459, n));
CROSSREFS
Cf. also A336549.
Subsequence of A336548, and probably also of A336560.
Sequence in context: A003925 A126846 A332150 * A158633 A204954 A204947
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 25 2020
STATUS
approved