A291756 Compound filter: a(n) = P(A003557(n), A000010(n)), where P(n,k) is sequence A000027 used as a pairing function.

1, 1, 2, 5, 7, 2, 16, 25, 31, 7, 46, 12, 67, 16, 29, 113, 121, 31, 154, 38, 67, 46, 232, 59, 281, 67, 334, 80, 379, 29, 436, 481, 191, 121, 277, 142, 631, 154, 277, 175, 781, 67, 862, 212, 328, 232, 1036, 261, 1135, 281, 497, 302, 1327, 334, 781, 355, 631, 379, 1654, 138, 1771, 436, 706, 1985, 1129, 191, 2146, 530, 947, 277, 2416, 607, 2557, 631, 951, 668, 1771

Offset

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..16385

Formula

a(n) = (1/2)*(2 + ((A003557(n)+A000010(n))^2) - A003557(n) - 3*A000010(n)).

Prog

(PARI)
A000010(n) = eulerphi(n);
A003557(n) = n/factorback(factor(n)[, 1]); \\ This function from Charles R Greathouse IV, Nov 17 2014
A291756(n) = (1/2)*(2 + ((A003557(n)+A000010(n))^2) - A003557(n) - 3*A000010(n));

Crossrefs

Cf. A000010, A000027, A003557, A291757, A291764.

Sequence in context: A093200 A095795 A088531 * A286463 A286362 A361118

Adjacent sequences: A291753 A291754 A291755 * A291757 A291758 A291759

Keyword

nonn

Author

Antti Karttunen, Sep 10 2017

Status

approved