OFFSET
0,7
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1350 (rows 0..20)
EXAMPLE
Triangle begins:
[0] 1;
[1] 1;
[2] 1, 1;
[3] 1, 1, 3, 2;
[4] 1, 1, 4, 10, 12, 10, 4;
[5] 1, 1, 4, 13, 41, 78, 131, 144, 107, 50, 12;
...
PROG
(PARI)
permcount(v) = {my(m=1, s=0, k=0, t); for(i=1, #v, t=v[i]; k=if(i>1&&t==v[i-1], k+1, 1); m*=t*k; s+=t); s!/m}
edges(v, t) = {prod(i=2, #v, prod(j=1, i-1, my(g=gcd(v[i], v[j])); t(v[i]*v[j]/g)^g )) * prod(i=1, #v, my(c=v[i]); t(c)^((c-1)\2))}
row(n)={my(s=0); forpart(p=n, s+=permcount(p)*edges(p, i->1+2*x^i)); Vecrev(s/n!)}
{ for(n=0, 6, print(row(n))) }
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Andrew Howroyd, Jan 13 2022
STATUS
approved