1,2

a(p) = 3, for primes p.

Antti Karttunen, Table of n, a(n) for n = 1..10000

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). [From Franklin T. Adams-Watters, Oct 09 2009]

(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

Also row sums of triangle A144515. - Gary W. Adamson, Nov 21 2007

Cf. A000005, A051731, A114002.

Sequence in context: A163167 A243729 A200810 * A219792 A029622 A015126

Adjacent sequences: A114000 A114001 A114002 * A114004 A114005 A114006

nonn

Paul Barry, Nov 12 2005

approved