A254572 Least multiple of n that is abundant or perfect (A023196).

6, 6, 6, 12, 20, 6, 28, 24, 18, 20, 66, 12, 78, 28, 30, 48, 102, 18, 114, 20, 42, 66, 138, 24, 100, 78, 54, 28, 174, 30, 186, 96, 66, 102, 70, 36, 222, 114, 78, 40, 246, 42, 258, 88, 90, 138, 282, 48, 196, 100, 102, 104, 318, 54, 220, 56, 114, 174, 354, 60

Offset

1,1

Comments

See A254571(n) = a(n)/n for the multipliers.

Very often a(n) = A064162(n), but the definition of the latter requires strict abundance.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

f:= proc(n) local k; uses numtheory;
      for k from 1 to 4 do if sigma(k*n)>=2*k*n then return k*n fi od:
      6*n
end proc:
map(f, [$1..100]); # Robert Israel, Feb 10 2019

Mathematica

a[n_] := Do[If[DivisorSigma[1, k*n] >= 2*k*n, Return[k*n]], {k, {1, 2, 3, 4, 6}}];
Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Feb 09 2023 *)

Prog

(PARI) a(n) = forstep(m=n, 6*n, n, if(sigma(m)>=2*m, return(m)))

Crossrefs

Cf. A023196, A064162, A254571.

Sequence in context: A315828 A315829 A180604 * A360561 A109047 A337814

Adjacent sequences: A254569 A254570 A254571 * A254573 A254574 A254575

Keyword

nonn

Author

Jeppe Stig Nielsen, Feb 01 2015

Status

approved