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A213754
Principal diagonal of the convolution array A213753.
3
1, 16, 111, 576, 2631, 11292, 46927, 191680, 775599, 3122076, 12531591, 50220912, 201088855, 804798268, 3220143903, 12882607872, 51534757599, 206148206268, 824612224663, 3298489794160, 13194045161031, 52776361000476
OFFSET
1,2
LINKS
FORMULA
a(n) = -3*2^n + 3*2^(2*n) - n*2^(n+1) - n^2.
a(n) = 11*a(n-1) - 47*a(n-2) + 101*a(n-3) - 116*a(n-4) + 68*a(n-5) - 16*a(n-6) for n>5. Corrected by Colin Barker, Nov 07 2017
G.f.: f(x)/g(x), where f(x) = x*(1 + 5*x - 18*x^2 + 6*x^3 + 12*x^4) and g(x) = (1 - 4*x) * (1 - x)^3 * (1 - 2*x)^2.
MATHEMATICA
(See A213753.)
PROG
(PARI) Vec(x*(1 + 5*x - 18*x^2 + 6*x^3 + 12*x^4) / ((1 - x)^3*(1 - 2*x)^2*(1 - 4*x)) + O(x^30)) \\ Colin Barker, Nov 07 2017
CROSSREFS
Sequence in context: A177046 A234250 A240786 * A371114 A279425 A144449
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 20 2012
STATUS
approved