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 A320468 a(n) = a(n-1) + 20*a(n-2), n >= 2; a(0)=1, a(1)=41. 2
 1, 41, 61, 881, 2101, 19721, 61741, 456161, 1690981, 10814201, 44633821, 260917841, 1153594261, 6371951081, 29443836301, 156882857921, 745759583941, 3883416742361, 18798608421181, 96466943268401, 472439111692021, 2401777977060041, 11850560210900461, 59886119752101281, 296897323970110501 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Index entries for linear recurrences with constant coefficients, signature (1,20). FORMULA a(n) = (-4)^(n+1) + 5^(n+1). G.f.: (1+40*x)/((1-5*x)*(1+4*x)). a(n) == 9*A053428(n)*A224473(n) mod 10^n. a(n)*A224473(n) == 9*A053428(n) mod 10^n. PROG (PARI) {a(n) = (-4)^(n+1)+5^(n+1)} (PARI) N=40; x='x+O('x^N); Vec((1+40*x)/((1-5*x)*(1+4*x))) CROSSREFS Cf. A053428, A224473 (trimorphic number), A320469, A321133. Sequence in context: A031415 A325072 A089345 * A055110 A245317 A039524 Adjacent sequences:  A320465 A320466 A320467 * A320469 A320470 A320471 KEYWORD nonn,easy AUTHOR Seiichi Manyama, Aug 27 2019 STATUS approved

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Last modified July 24 00:28 EDT 2021. Contains 346265 sequences. (Running on oeis4.)