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 A131607 Pell companion numbers A001333 without last digit. 1
 1, 4, 9, 23, 57, 139, 336, 811, 1960, 4732, 11424, 27580, 66585, 160752, 388089, 936931, 2261953, 5460839, 13183632, 31828103, 76839840, 185507784, 447855408, 1081218600, 2610292609, 6301803820, 15213900249, 36729604319, 88673108889, 214075822099, 516824753088 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,2 LINKS Andrew Howroyd, Table of n, a(n) for n = 4..1000 FORMULA a(n) = floor(A001333(n) / 10). - Andrew Howroyd, Jan 02 2020 Conjectures from Colin Barker, Jan 03 2020: (Start) G.f.: x^4*(1 + x - 2*x^2 + x^3 + x^4) / ((1 - x)*(1 + x^2)*(1 - 2*x - x^2)*(1 - x^2 + x^4)). a(n) = 3*a(n-1) - a(n-2) - a(n-3) - a(n-6) + 3*a(n-7) - a(n-8) - a(n-9) for n>12. (End) MATHEMATICA Table[Floor[(((1 - Sqrt[2])^n + (1 + Sqrt[2])^n)/2)/10], {n, 4, 29}] (* Metin Sariyar, Jan 03 2020 *) PROG (PARI) a(n)={polcoef((1 - x) / (1 - 2*x - x^2) + O(x*x^n), n)\10} \\ Andrew Howroyd, Jan 02 2020 CROSSREFS Cf. A001333, A131727. Sequence in context: A138990 A014543 A343676 * A221313 A238832 A192473 Adjacent sequences: A131604 A131605 A131606 * A131608 A131609 A131610 KEYWORD nonn,base AUTHOR Paul Curtz, Oct 02 2007 EXTENSIONS Offset changed and terms a(24) and beyond from Andrew Howroyd, Jan 02 2020 STATUS approved

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Last modified January 27 08:34 EST 2023. Contains 359837 sequences. (Running on oeis4.)