A024399 a(n) = [ (3rd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ], where S(n) = {first n+2 positive integers congruent to 2 mod 3}.

5, 31, 101, 248, 515, 952, 1619, 2586, 3930, 5738, 8107, 11141, 14954, 19670, 25420, 32345, 40596, 50331, 61718, 74935, 90167, 107609, 127466, 149950, 175283, 203697, 235431, 270734, 309865, 353090, 400685, 452936, 510136, 572588, 640605, 714507

Offset

1,1

Links

Table of n, a(n) for n=1..36.

Formula

Conjecture: a(n)= +4*a(n-1) -6*a(n-2) +5*a(n-3) -5*a(n-4) +6*a(n-5) -4*a(n-6) +a(n-7). G.f. x*(-5-11*x-7*x^2-5*x^3+x^4) / ( (1+x+x^2)*(x-1)^5 ). - R. J. Mathar, Oct 08 2011

a(n) = floor(A024392(n) / A005449(n + 2)). - Sean A. Irvine, Jul 06 2019

Crossrefs

Cf. A024392, A005449.

Sequence in context: A115519 A211923 A362304 * A183520 A099083 A212523

Adjacent sequences: A024396 A024397 A024398 * A024400 A024401 A024402

Keyword

nonn

Author

Clark Kimberling

Status

approved