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A025136
a(n) = 2nd elementary symmetric function of C(n,0), C(n,1), ..., C(n,[ n/2 ]).
1
2, 3, 34, 65, 551, 1190, 8842, 20613, 141457, 347930, 2260567, 5788458, 36110426, 95438348, 576758282, 1564082093, 9212023037, 25523422418, 147143150689, 415191345278, 2350493291126, 6737735340308, 37550466036439
OFFSET
2,1
LINKS
MAPLE
g:= proc(L) local i, j, m;
m:= nops(L);
add(add(L[i]*L[j], j=1..i-1), i=2..m)
end proc:
seq(g([seq(binomial(n, i), i=0..n/2)]), n=2..30); # Robert Israel, Oct 31 2024
CROSSREFS
Sequence in context: A032816 A073657 A228114 * A195030 A347338 A092981
KEYWORD
nonn,changed
STATUS
approved