OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..500
FORMULA
a(n) = [x^prime(2*n)] Product_{k=1..2*n} (x^prime(k) + 1/x^prime(k)).
MAPLE
M:= 80: # for a(1) .. a(M/2)
N:= add(ithprime(i), i=1..M): m:= 0: p:= 1: R:= NULL: V:= Vector(2*N+1): V[1]:= 1:
for i from 1 to M do
p:= ithprime(i);
V[1+2*p..m+1+2*p]:= V[1+2*p .. m+1+2*p] + V[1..m+1];
if i::even then R:= R, V[1+m/2+2*p] fi;
m:= m + 2*p;
od:
R; # Robert Israel, Apr 29 2026
MATHEMATICA
Table[Coefficient[Product[(x^Prime[k] + 1/x^Prime[k]), {k, 1, 2 n}], x, Prime[2 n]], {n, 1, 28}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jan 27 2024
STATUS
approved
