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A067951
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a(0) = 1; a(n) = Sum_{1 <= k <= n and k|n} a(n-k).
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3
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1, 1, 2, 3, 6, 7, 17, 18, 42, 60, 110, 111, 341, 342, 702, 1154, 2240, 2241, 6037, 6038, 15580, 22320, 38012, 38013, 122544, 138125, 261012, 389594, 796173, 796174, 2259345, 2259346, 5439649, 7737007, 13178898, 16234417, 45367492, 45367493
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OFFSET
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0,3
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COMMENTS
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LINKS
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MAPLE
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f:=proc(n) option remember;
add(procname(n-k), k=numtheory:-divisors(n))
end proc:
f(0):= 1:
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MATHEMATICA
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a[0] = 1; a[n_] := a[n] = Sum[a[n - k], {k, Divisors@ n}]; Table[a@ n, {n, 0, 37}] (* Michael De Vlieger, Sep 13 2016 *)
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PROG
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(PARI) a(n)=if (n==0, return(1)); my(an = 0); fordiv(n, k, an += a(n-k)); an; \\ Michel Marcus, Jul 14 2013
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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