1,3

Right border of A299762. - Omar E. Pol, Mar 14 2018

Amiram Eldar, Table of n, a(n) for n = 1..10000

x = 11 is the largest x such that sigma(x) = 12, so a(12) = 11.

a[n_] := Module[{k = n}, While[k > 0 && DivisorSigma[1, k] != n, k--]; k]; Array[a, 90] (* Amiram Eldar, Jan 05 2020 *)

Cf. A000203, A051444, A054973, A299762.

Sequence in context: A240667 A051444 A299762 * A258913 A167485 A294141

Adjacent sequences: A057634 A057635 A057636 * A057638 A057639 A057640

nonn

Jud McCranie, Oct 10 2000

approved