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A291756 Compound filter: a(n) = P(A003557(n), A000010(n)), where P(n,k) is sequence A000027 used as a pairing function. 7
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 (list; graph; refs; listen; history; text; internal format)
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 A309200

Adjacent sequences:  A291753 A291754 A291755 * A291757 A291758 A291759

KEYWORD

nonn

AUTHOR

Antti Karttunen, Sep 10 2017

STATUS

approved

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Last modified May 18 03:03 EDT 2021. Contains 343994 sequences. (Running on oeis4.)