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A005421
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Number of numbers of complexity n, i.e., that can be built from n ones using + and *, and require at least that many ones.
(Formerly M0430)
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12
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1, 1, 1, 1, 2, 3, 2, 6, 6, 7, 14, 16, 20, 34, 42, 56, 84, 108, 152, 214, 295, 398, 569, 763, 1094, 1475, 2058, 2878, 3929, 5493, 7669, 10501, 14707, 20476, 28226, 39287, 54817, 75619, 105584, 146910, 203294, 283764, 394437, 547485, 763821, 1061367, 1476067, 2057708, 2861449
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OFFSET
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1,5
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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MATHEMATICA
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terms = 30;
kmax = 60000;
cpx[1] = 1; cpx[k_] := cpx[k] = Min[Sequence @@ Table[cpx[i] + cpx[k-i], {i, 1, k/2}], Sequence @@ Table[cpx[d] + cpx[k/d], {d, Divisors[k][[2 ;; -2]]}]];
Clear[a]; a[_] = 0;
Do[n = cpx[k]; a[n] += 1, {k, 1, kmax}];
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CROSSREFS
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KEYWORD
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nonn,nice
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AUTHOR
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EXTENSIONS
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More terms from Tim Peters (tim.one(AT)comcast.net), Nov 12 2004
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STATUS
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approved
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