OFFSET
0,3
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..2713 (rows 0..20)
S.-H. Cha, E. G. DuCasse, and L. V. Quintas, Graph Invariants Based on the Divides Relation and Ordered by Prime Signatures, arXiv:1405.5283 [math.NT], 2014, Table A.1 entry |P^T(s)|.
FORMULA
EXAMPLE
Triangle T(n,k) begins:
1;
1;
2, 3;
4, 8, 13;
8, 20, 26, 44, 75;
16, 48, 76, 132, 176, 308, 541;
32, 112, 208, 252, 368, 604, 818, 1076, 1460, 2612, 4683;
...
PROG
(PARI) \\ here b(n) is A074206.
N(sig)={prod(k=1, #sig, prime(k)^sig[k])}
b(n)={if(!n, 0, my(sig=factor(n)[, 2], m=vecsum(sig)); sum(k=0, m, prod(i=1, #sig, binomial(sig[i]+k-1, k-1))*sum(r=k, m, binomial(r, k)*(-1)^(r-k))))}
Row(n)={apply(s->b(N(s)), [Vecrev(p) | p<-partitions(n)])}
{ for(n=0, 6, print(Row(n))) } \\ Andrew Howroyd, Aug 30 2020
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Sung-Hyuk Cha, Mar 07 2014
EXTENSIONS
Offset changed and terms a(44) and beyond from Andrew Howroyd, Apr 25 2020
STATUS
approved