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A126761 {a(k)} is such that, for every positive integer n, the n-th prime = Sum_{k=1..n, gcd(k,n+1)=1} a(k). 1
2, 1, 3, 1, 9, -3, 3, 3, 15, -5, 17, -9, -5, 21, 3, -3, 33, -25, -1, 19, 11, -11, 25, 11, -23, 15, 25, -25, 35, -29, -25, 51, 43, -59, 79, -51, -93, 109, 79, -73, 205, -197, -189, 83, -29, 153, 139, -223, -95, -193, 41, 371, 125, -223, -177, -151, 49, 409, 101 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Rémy Sigrist, PARI program for A126761

EXAMPLE

31 is the 11th prime. So 31 = Sum_{1<=k<=11, gcd(k,12)=1} a(k) = a(1) + a(5) + a(7) + a(11) = 2 + 9 + 3 + 17.

PROG

(PARI) See Links section.

CROSSREFS

Cf. A000040.

Sequence in context: A136179 A185176 A198315 * A090559 A186725 A301935

Adjacent sequences:  A126758 A126759 A126760 * A126762 A126763 A126764

KEYWORD

sign

AUTHOR

Leroy Quet, Feb 22 2007

EXTENSIONS

More terms from Rémy Sigrist, Feb 06 2019

STATUS

approved

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Last modified February 27 07:03 EST 2020. Contains 332299 sequences. (Running on oeis4.)