A157056 Number of integer sequences of length n+1 with sum zero and sum of absolute values 14.

2, 42, 492, 4060, 26070, 137886, 623576, 2476296, 8809110, 28512110, 85014204, 235895244, 614266354, 1511679210, 3536846160, 7907476016, 16967926746, 35078339106, 70098276620, 135798494460, 255689552382, 468969729382, 839584669992, 1469778991800, 2520031983950

Offset: 1

Author

R. H. Hardin, Feb 22 2009

Keywords

• nonn
• easy

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (15,-105,455,-1365,3003,-5005,6435,-6435,5005,-3003,1365,-455,105,-15,1).

Crossrefs

Cf. A103881, A156554.

Programs

Mathematica

Table[n*(n+1)*(n^12 +6*n^11 +197*n^10 +930*n^9 +12363*n^8 +43938*n^7 +300551*n^6 +751710*n^5 +2756536*n^4 +4309656*n^3 +7816752*n^2 +5780160*n +3628800)/25401600, {n,50}] (* G. C. Greubel, Jan 24 2022 *)

Sage

[n*(n+1)*(n^12 +6*n^11 +197*n^10 +930*n^9 +12363*n^8 +43938*n^7 +300551*n^6 +751710*n^5 +2756536*n^4 +4309656*n^3 +7816752*n^2 +5780160*n +3628800)/25401600 for n in (1..50)] # G. C. Greubel, Jan 24 2022

Formula

a(n) = T(n,7); T(n,k) = Sum_{i=1..n} binomial(n+1,i)*binomial(k-1,i-1)*binomial(n-i+k,k).

G.f.: 2*x*(1 +6*x +36*x^2 +90*x^3 +225*x^4 +300*x^5 +400*x^6 +300*x^7 +225*x^8 +90*x^9 +36*x^10 +6*x^11 +x^12)/(1-x)^15. - Colin Barker, Jan 25 2013

From G. C. Greubel, Jan 24 2022: (Start)

a(n) = n*(n+1)*(n^12 +6*n^11 +197*n^10 +930*n^9 +12363*n^8 +43938*n^7 +300551*n^6 +751710*n^5 +2756536*n^4 +4309656*n^3 +7816752*n^2 +5780160*n +3628800)/25401600.

E.g.f.: (x/25401600)*(50803200 [phone]*x [phone]*x^2 [phone]*x^3 [phone]*x^4 [phone]*x^5 [phone]*x^6 [phone]*x^7 [phone]*x^8 +1449420*x^9 +97608*x^10 +4116*x^11 +98*x^12 +x^13)*exp(x). (End)