A376156 a(n) is the least number that is the sum of the nonprime divisors of k for exactly n different k.

2, 5, 23, 83, 536, 2519, 45359, 16736, 743398, 1908958, 3386606, 9295535

Offset

0,1

Links

Table of n, a(n) for n=0..11.

Example

2 is not the sum of the nonprime divisors of any k.
5 is the sum of the nonprime divisors of 4 (1 + 4 = 5).
23 is the sum of the nonprime divisors of 12 (1 + 4 + 6 + 12) and of 22 (1 + 22).
83 is the sum of the nonprime divisors of 40 (1 + 4 + 8 + 10 + 20 + 40) and 52 (1 + 4 + 26 + 52) and 82 (1 + 82).

Maple

N:= 10^6: # for terms < 10^6
f:= proc(n) convert(remove(isprime, numtheory:-divisors(n)), `+`) end proc:
R:= Vector(N):
for i from 1 to N do
  v:= f(i);
  if v <= N then R[v]:= R[v]+1 fi
od:
m:= convert(R, set)[-2]:
V:= Array(0..m): count:= 0:
for i from 2 while count < m+1 do
if V[R[i]] = 0 then V[R[i]]:= i; count:= count+1 fi
od:
convert(V, list);

Crossrefs

Cf. A023890.

Sequence in context: A395474 A106858 A380852 * A290887 A219889 A369834

Adjacent sequences: A376153 A376154 A376155 * A376157 A376158 A376159

Keyword

nonn,more

Author

Robert Israel, Sep 12 2024

Status

approved