|
%I #6 Aug 26 2015 00:54:06
%S 1,1,2,7,24,86,316,1177,4424,16744,63724,243618,934870,3598960,
%T 13892776,53756263,208434024,809658440,3150218032,12274694280,
%U 47890456576,187068828772,731511810152,2863308366462,11217762520246,43984983838966
%N Main diagonal of triangle A131823: a(n) = A131823(n,n) for n>=0.
%F a(n) = [x^n] Product_{i=0..n-1} (1 + x^(2^i))^(n-i) for n>=0.
%p A131824 := proc(n) local f,i ; f := 1 ; if n = 1 then RETURN(1) ; fi ; for i from 0 to n-1 do f := taylor(f*(1+x^(2^i))^(n-i),x=0,n+1) ; od; coeftayl(f,x=0,n) ; end: seq(A131824(n),n=0..27) ; # _R. J. Mathar_, Jul 24 2007
%o (PARI) a(n)=if(n==0,1,polcoeff(prod(i=0,n-1,(1 + x^(2^i) +x*O(x^n))^(n-i)), n))
%Y Cf. A131823.
%K nonn
%O 0,3
%A _Paul D. Hanna_, Jul 19 2007
%E More terms from _R. J. Mathar_, Jul 24 2007
|
