A024385 a(n) = [ (2nd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ], where S(n) = {first n+1 positive integers congruent to 1 mod 4}.

0, 3, 9, 16, 25, 36, 49, 64, 82, 101, 122, 145, 170, 197, 227, 258, 291, 326, 363, 402, 444, 487, 532, 579, 628, 679, 733, 788, 845, 904, 965, 1028, 1094, 1161, 1230, 1301, 1374, 1449, 1527, 1606, 1687, 1770, 1855, 1942

Offset

1,2

Links

Table of n, a(n) for n=1..44.

Formula

Conjecture: a(n) = 2*a(n-1) - a(n-2) + a(n-6) - 2*a(n-7) + a(n-8). G.f. x^2*(-3-3*x-x^2-2*x^3-2*x^4-2*x^5+x^6) / ( (1+x)*(1+x+x^2)*(x^2-x+1)*(x-1)^3 ). - R. J. Mathar, Oct 08 2011

a(n) = floor(A024378(n) / A000384(n+1)). - Sean A. Irvine, Jul 06 2019

Crossrefs

Sequence in context: A109340 A339918 A354258 * A212566 A061942 A174440

Adjacent sequences: A024382 A024383 A024384 * A024386 A024387 A024388

Keyword

nonn

Author

Clark Kimberling

Status

approved