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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A355687 Sum of A276150 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 3, 4, 6, 0, 4, 0, 4, 12, 3, 0, -2, 0, 9, 8, 8, 0, -3, 9, 6, 4, 8, 0, -10, 0, 5, 16, 10, 12, 6, 0, 8, 12, -1, 0, 2, 0, 14, -2, 12, 0, 12, 4, 1, 20, 13, 0, 14, 24, 7, 16, 14, 0, -14, 0, 4, 8, 3, 18, -14, 0, 11, 24, 2, 0, 20, 0, 6, -10, 10, 16, -2, 0, 9, 13, 10, 0, 1, 30, 8, 28, -3, 0, 28, 12, 16
Offset: 1

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Author

Antti Karttunen, Jul 14 2022

Keywords

Links

Crossrefs

Cf. A276150, A355686.

Programs

  • PARI
    A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
memoA355686 = Map();
A355686(n) = if(1==n,1,my(v); if(mapisdefined(memoA355686,n,&v), v, v = -sumdiv(n,d,if(dA276150(n/d)*A355686(d),0)); mapput(memoA355686,n,v); (v)));
A355687(n) = (A276150(n)+A355686(n));

Formula

a(n) = A276150(n) + A355686(n).
a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A276150(d) * A355686(n/d).
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