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 A049996 a(n) is the index k such that F(k)=d(n), where d=A049874 (difference sequence of ordered products of Fibonacci numbers). 1
 1, 1, 1, 3, 1, 3, 3, 4, 3, 1, 5, 4, 3, 6, 5, 1, 3, 7, 6, 3, 4, 8, 7, 3, 1, 5, 9, 8, 4, 3, 6, 10, 9, 5, 1, 3, 7, 11, 10, 6, 3, 4, 8, 12, 11, 7, 3, 1, 5, 9, 13, 12, 8, 4, 3, 6, 10, 14, 13, 9, 5, 1, 3, 7, 11, 15, 14, 10, 6, 3, 4, 8, 12, 16, 15, 11, 7, 3, 1, 5, 9, 13, 17 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Michel Marcus, Table of n, a(n) for n = 1..1010 MATHEMATICA Block[{nn = 123, s, t}, s = Differences@ Take[#, nn] &@ Union@ Flatten[Table[Fibonacci[i]*Fibonacci[j], {i, 0, nn}, {j, i + 1, nn}]]; t = Fibonacci@ Range@ nn; Array[First@ FirstPosition[t, s[[#]] ] &, Length@ s]] (* Michael De Vlieger, May 27 2019 *) PROG (PARI) ifib(n) = if (n==1, 1, log(n*sqrt(5) + 1/2)\log((1+sqrt(5))/2)); lista(nn) = {my(out = List([0])); for (i=0, nn, for (j=i+1, nn, listput(out, fibonacci(i)*fibonacci(j)); ); ); my(v = Vec(vecsort(select(x->(x < fibonacci(nn+1)), out), , 8))); my(w = vector(#v-1, k, v[k+1] - v[k])); vector(#w, k, ifib(w[k])); } \\ Michel Marcus, May 27 2019 CROSSREFS Cf. A049862, A049874. Sequence in context: A136297 A243339 A244965 * A143908 A117572 A029153 Adjacent sequences:  A049993 A049994 A049995 * A049997 A049998 A049999 KEYWORD nonn AUTHOR EXTENSIONS More terms from Michel Marcus, May 27 2019 STATUS approved

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Last modified October 14 16:40 EDT 2019. Contains 328022 sequences. (Running on oeis4.)