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 A144689 A098777 mod 7. 2
 1, 6, 5, 2, 2, 2, 2, 4, 1, 6, 6, 6, 6, 5, 3, 4, 4, 4, 4, 1, 2, 5, 5, 5, 5, 3, 6, 1, 1, 1, 1, 2, 4, 3, 3, 3, 3, 6, 5, 2, 2, 2, 2, 4, 1, 6, 6, 6, 6, 5, 3, 4, 4, 4, 4, 1, 2, 5, 5, 5, 5, 3, 6, 1, 1, 1, 1, 2, 4, 3, 3, 3, 3, 6, 5, 2, 2, 2, 2, 4, 1, 6, 6, 6, 6, 5, 3, 4, 4, 4, 4, 1, 2, 5, 5, 5, 5, 3, 6, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Muniru A Asiru, Table of n, a(n) for n = 0..1000 R. Bacher and P. Flajolet, Pseudo-factorials, Elliptic Functions and Continued Fractions, arXiv:0901.1379 [math.CA], 2009. FORMULA For n >= 0 has period 36. From Chai Wah Wu, Jun 09 2016: (Start) a(n) = a(n-1) - a(n-18) + a(n-19) for n > 19. G.f.: (1 + 5*x - x^2 - 3*x^3 + 2*x^7 - 3*x^8 + 5*x^9 - x^13 - 2*x^14 + x^15 + x^18 + 2*x^19)/(1 - x + x^18 - x^19). (End) MAPLE a:= proc(n) option remember; `if`(n=0, 1, (-1)^n*add(binomial(n-1, k)*a(k)*a(n-1-k), k=0..n-1)) end: seq(modp(a(n), 7), n=0..100); # Muniru A Asiru, Jul 29 2018 MATHEMATICA b[0] = 1; b[n_] := b[n] = (-1)^n Sum[Binomial[n-1, k] b[k] b[n-k-1], {k, 0, n-1}]; a[n_] := Mod[b[n], 7]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Jul 29 2018 *) CROSSREFS Sequence in context: A177938 A112282 A098866 * A221215 A199180 A197265 Adjacent sequences:  A144686 A144687 A144688 * A144690 A144691 A144692 KEYWORD nonn AUTHOR N. J. A. Sloane, Feb 08 2009 STATUS approved

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Last modified April 12 18:58 EDT 2021. Contains 342932 sequences. (Running on oeis4.)