OFFSET
1,2
COMMENTS
a(n)==1 (mod n+1). E.g., a(4)=116 and 116==1 (mod 5), a(11)=5401 and 5401==1 (mod 12).
Inverse binomial transform of this sequence: 1, 9, 22, 22, 8, 0, 0 (0 continued).
LINKS
B. Berselli, Table of n, a(n) for n = 1..10000.
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n) = n*(n^3+n^2+2*n-1)/3.
G.f.: x*(1+5*x+x^2+x^3)/(1-x)^5.
a(n) = 5*a(n-1)-10*a(n-2)+10*a(n-3)-5*a(n-4)+a(n-5) with n>5.
a(n)+a(-n) = A035598(n). [Bruno Berselli, Jun 21 2012]
PROG
(Magma) A177342:=func<n | (4*n^3-3*n^2+5*n-3)/3>; [&+[A177342(i): i in [1..n]]: n in [1..35]]; // Bruno Berselli, Jun 21 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Bruno Berselli, May 31 2010
EXTENSIONS
Edited by Bruno Berselli, Dec 29 2010
STATUS
approved