%I A108490
%S A108490 1,2,10,56,268,1448,7864,42752,236368,1313696,7339552,41217920,
%T A108490 232321984,1313731712,7449834880,42347380736,241225384192,1376662561280,
%U A108490 7869527190016,45051709749248,258256281078784,1482218578159616
%N A108490 Expansion of 1/sqrt(1-4x-8x^2-24x^3+36x^4).
%C A108490 In general, sum{k=0..n, C(n-k,k)^2*a^k*b^(n-k)} has expansion 1/sqrt(1-2bx-(2ab-b^2)x^2-2a*b^2*x^3+(ab)^2*x^4\
               ).
%F A108490 a(n)=sum{k=0..n, C(n-k, k)^2*3^k*2^(n-k)}.
%Y A108490 Cf. A108486.
%Y A108490 Sequence in context: A163909 A152395 A122826 this_sequence A165817 A000172 
               A097971
%Y A108490 Adjacent sequences: A108487 A108488 A108489 this_sequence A108491 A108492 
               A108493
%K A108490 easy,nonn
%O A108490 0,2
%A A108490 Paul Barry (pbarry(AT)wit.ie), Jun 04 2005