A283524 a(n) is the smallest k such that there is no x with sigma(x) = k*n.

2, 1, 3, 4, 1, 11, 3, 2, 1, 1, 1, 23, 2, 5, 3, 1, 1, 27, 1, 5, 1, 1, 1, 73, 1, 1, 1, 7, 1, 25, 5, 2, 1, 1, 1, 71, 1, 2, 3, 13, 1, 71, 1, 2, 1, 1, 1, 73, 1, 1, 1, 1, 1, 9, 1, 23, 5, 1, 1, 29, 1, 5, 3, 1, 1, 1, 1, 2

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Prog

(PARI) do(x)=my(v=List(), u=vectorsmall(x\1), t, n); for(k=1, x, t=sigma(k); if(t<=x, u[t]=1)); while(1, forstep(k=n++, x, n, if(u[k]==0, listput(v, k/n); next(2))); return(Vec(v))) \\ Charles R Greathouse IV, Mar 12 2017

Crossrefs

Cf. A007369, A000203.

Sequence in context: A249042 A262472 A049400 * A106382 A229287 A286539

Adjacent sequences: A283521 A283522 A283523 * A283525 A283526 A283527

Keyword

nonn

Author

Juri-Stepan Gerasimov, Mar 09 2017

Extensions

Corrected and extended by Charles R Greathouse IV, Mar 12 2017

Status

approved