A181324 - OEIS

%I #9 Sep 07 2015 13:14:01

%S 1,1,1,1,1,2,3,4,5,6,8,11,16,22,29,38,50,68,93,126,169,225,302,407,

%T 550,742,997,1339,1799,2421,3261,4390,5906,7941,10680,14371,19341,

%U 26028,35017,47105,63370,85261,114723,154360,207679,279405,375907,505759,680479,915554,1231813

%N G.f. 1/(1-sum(n=1,N,x^(n*(3*n-1)/2)))

%C Number of compositions into positive pentagonal numbers (A000326). [_Joerg Arndt_, Jun 10 2011]

%o (PARI) N=99; x='x+O('x^N);

%o Vec(1/(1-sum(n=1,N,x^(n*(3*n-1)/2)))) /* show terms */

%Y A023361 ( g.f. 1/(1-sum(n=1,N,x^(n*(n+1)/2))) ).

%K nonn

%O 0,6

%A _Joerg Arndt_, Jan 27 2011