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A114003
Rows sums of triangle A114002.
8
1, 3, 3, 5, 3, 7, 3, 7, 5, 7, 3, 11, 3, 7, 7, 9, 3, 11, 3, 11, 7, 7, 3, 15, 5, 7, 7, 11, 3, 15, 3, 11, 7, 7, 7, 17, 3, 7, 7, 15, 3, 15, 3, 11, 11, 7, 3, 19, 5, 11, 7, 11, 3, 15, 7, 15, 7, 7, 3, 23, 3, 7, 11, 13, 7, 15, 3, 11, 7, 15, 3, 23, 3, 7, 11, 11, 7, 15, 3, 19, 9, 7, 3, 23, 7, 7, 7, 15, 3, 23, 7, 11, 7, 7, 7, 23, 3
OFFSET
1,2
LINKS
FORMULA
a(p) = 3, for primes p.
a(n) = 2*A000005(n) - 1. - Vladeta Jovovic, Sep 13 2006
Equals A051731 * [1, 2, 2, 2, ...]. - Gary W. Adamson, Sep 21 2007
G.f.: Sum_{n>0} x^n*(1+x^n)/(1-x^n). - Franklin T. Adams-Watters, Oct 09 2009
MATHEMATICA
Table[2 DivisorSigma[0, n]-1, {n, 97}] (* Stefano Spezia, Sep 08 2023 *)
PROG
(PARI) N=66; x='x+O('x^N); /* that many terms */
Vec(sum(n=1, N, x^n*(1+x^n)/(1-x^n))) /* show terms */ /* Joerg Arndt, May 25 2011 */
(PARI) A114003(n) = (2*numdiv(n))-1; \\ After Jovovic's formula. Antti Karttunen, May 25 2017
CROSSREFS
Also row sums of triangle A144515. - Gary W. Adamson, Nov 21 2007
Sequence in context: A243729 A200810 A365710 * A219792 A029622 A015126
KEYWORD
nonn
AUTHOR
Paul Barry, Nov 12 2005
STATUS
approved