A340715 Least positive number k such that sigma(k+1) = n * sigma(k).
14, 5, 1, 37033919, 14182439039
Offset: 1
Examples
n | sigma(a(n)) | sigma(a(n)+1) ----+-------------+-------------- 1 | 24 | 24 2 | 6 | 12 3 | 1 | 3 4 | 39940992 | 159763968 5 | 14182439040 | 70912195200
Programs
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Mathematica
k = 1;n = 1;Print[While[DivisorSigma[1, k + 1] != n*DivisorSigma[1, k], k;k k+]; k] (* Robert P. P. McKone, Jan 17 2021 *)
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PARI
{a(n) = my(k=1); while(sigma(k+1)!=n*sigma(k), k++); k}