A336561 Numbers k at which point A336459(k) appears multiplicative, but A051027(k) does not.

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

Links

Antti Karttunen, Table of n, a(n) for n = 1..11481

Index entries for sequences related to sigma(n)

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));
A336459(n) = A065330(A051027(n));
isA336561(n) = (A336546(n)<is_fun_mult_on_n(A336459, n));

Crossrefs

Cf. A051027, A065330, A336459.

Cf. also A336549.

Subsequence of A336548, and probably also of A336560.

Sequence in context: A003925 A126846 A332150 * A158633 A204954 A204947

Adjacent sequences: A336558 A336559 A336560 * A336562 A336563 A336564

Keyword

nonn

Author

Antti Karttunen, Jul 25 2020

Status

approved