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A115285
Diagonal sums of correlation triangle for 1,3,4,4,4,...(A113311).
1
1, 3, 7, 14, 23, 35, 50, 67, 87, 110, 135, 163, 194, 227, 263, 302, 343, 387, 434, 483, 535, 590, 647, 707, 770, 835, 903, 974, 1047, 1123, 1202, 1283, 1367, 1454, 1543, 1635, 1730, 1827, 1927, 2030, 2135, 2243, 2354, 2467, 2583, 2702, 2823, 2947, 3074
OFFSET
0,2
COMMENTS
Diagonal sums of number triangle A115284.
FORMULA
G.f.: (1+x)^2*(1+x^2)^2/((1-x)(1-x^2)(1-x^3)); a(n)=sum{k=0..floor(n/2), sum{j=0..n-k [j<=k]*(4-C(1, k-j)-2C(0, k-j))*[j<=n-2k]*((4-C(1, n-2k-j)-2C(0, n-2k-j))}}.
MATHEMATICA
LinearRecurrence[{2, -1, 1, -2, 1}, {1, 3, 7, 14, 23, 35}, 50] (* Harvey P. Dale, Jul 27 2015 *)
CROSSREFS
Sequence in context: A377122 A213077 A294400 * A004232 A140462 A227841
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jan 19 2006
STATUS
approved