OFFSET
1,3
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..200
PROG
(PARI) \\ Ach is A304972 as square matrix.
Ach(n)={my(M=matrix(n, n, i, k, i>=k)); for(i=3, n, for(k=2, n, M[i, k]=k*M[i-2, k] + M[i-2, k-1] + if(k>2, M[i-2, k-2]))); M}
seq(n)={my(A=Ach(n)); vector(n, i, sum(k=1, n, (A[i, k] + stirling(i, k, 2))/2 - stirling((i+1)\2, k, 2)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Sep 18 2019
STATUS
approved