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A171844
Row sums of triangle A171843.
2
1, 4, 12, 31, 77, 188, 462, 1148, 2887, 7335, 18789, 48419, 125321, 325381, 846713, 2206891, 5758797, 15040102, 39304237, 102760572, 268757551, 703079117, 1839625401, 4814107671, 12599351527, 32977310272, 86319400527, 225954695164, 591492569038, 1548419254590
OFFSET
1,2
LINKS
FORMULA
G.f.: Sum_{k>=1} x^k*(1 - x^k)/((1 - x)*(1 - 2*x + x^2 - x^k)). - Andrew Howroyd, Apr 13 2021
EXAMPLE
a(4) = 31 = (1 + 3 + 6 + 21) since row 4 of triangle A171843 = (1, 3, 6, 21).
PROG
(PARI) seq(n)={Vec(sum(k=1, n, x^k*(1 - x^k)/((1 - x)*(1 - 2*x + x^2 - x^k)) + O(x*x^n)))} \\ Andrew Howroyd, Apr 13 2021
CROSSREFS
Cf. A171843.
Sequence in context: A133546 A190376 A276785 * A324971 A273387 A328240
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Dec 19 2009
EXTENSIONS
a(10) and a(13) corrected and a(14) and beyond from Andrew Howroyd, Apr 13 2021
STATUS
approved