A320626 a(n) = (A006134(prime(n)-1) - Legendre(prime(n), 3))/prime(n)^2.
1, 1, 4, 26, 2074, 21660, 2804068, 33847970, 5345496688, 12201269878660, 165029257057602, 433037204976615540, 85637003420093445994, 1215603499085916654728, 248871244937134915010626, 753881874165723132009014662, 2359161060012378685209851991166
Offset: 1
Keywords
Examples
a(1) = (binomial(0, 0) + binomial(2, 1) + 1)/4 = 4/4 = 1. a(2) = (binomial(0, 0) + binomial(2, 1) + binomial(4, 2))/9 = 9/9 = 1. a(3) = (binomial(0, 0) + binomial(2, 1) + binomial(4, 2) + binomial(6, 3) + binomial(8, 4) + 1)/25 = 100/25 = 4.
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