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A256960
a(0)=1, a(1)=4; thereafter a(n) = a(n-2)+2*A055099(n-1)+2^(n-1).
1
1, 4, 11, 36, 119, 408, 1419, 4988, 17631, 62528, 222163, 790180, 2812135, 10011304, 35647259, 126942540, 452078447, 1610033040, 5734081251, 20421960308, 72733344375, 259042555640, 922591559467, 3285854197276, 11702734525951, 41679889602784, 148445093121011, 528694969090116
OFFSET
0,2
LINKS
J. Goldwasser et al., The density of ones in Pascal's rhombus, Discrete Math., 204 (1999), 231-236.
Paul K. Stockmeyer, The Pascal Rhombus and the Stealth Configuration, arXiv:1504.04404 [math.CO], 2015.
FORMULA
G.f.: -(2*x+1)*(2*x^2+2*x-1) / ((x+1)*(2*x-1)*(2*x^2+3*x-1)). - Colin Barker, Jun 05 2015
PROG
(PARI) Vec(-(2*x+1)*(2*x^2+2*x-1)/((x+1)*(2*x-1)*(2*x^2+3*x-1)) + O(x^100)) \\ Colin Barker, Jun 06 2015
CROSSREFS
Cf. A055099.
Sequence in context: A206687 A106640 A109268 * A174993 A149238 A149239
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Apr 14 2015
STATUS
approved