A067846 Least m such that A067513(m) = n.

1, 2, 4, 16, 12, 48, 36, 60, 120, 252, 180, 480, 360, 540, 720, 1080, 1620, 1260, 1680, 2160, 3600, 2520, 3780, 6720, 6480, 9240, 5040, 7560, 15840, 16380, 10080, 22680, 18480, 32400, 20160, 15120, 37800, 32760, 25200, 40320, 30240, 73920, 45360

Offset: 1

Author

Vladeta Jovovic, Feb 14 2002

Keywords

• nonn

Comments

There are 57 terms less than 200000. - David Wasserman, Dec 20 2002

Links

• Robert G. Wilson v, Table of n, a(n) for n = 1..1276 (first 161 terms from Robert Israel)

Crossrefs

Cf. A067513, A183063.

Programs

Maple

N:= 80: # to get a(1)..a(N)
A067513:= n -> nops(select(t -> isprime(t+1), numtheory:-divisors(n))):
A:= Vector(N):
count:= 1: A[1]:= 1:
for n from 2 by 2 while count < N do
  v:= A067513(n);
  if v <= N and A[v]=0 then A[v]:= n; count:= count+1; fi
od:
convert(A, list); # Robert Israel, Jun 08 2018

PARI

a067513(n) = sumdiv(n, d, isprime(d+1));
a(n) = {my(k=1); while(a067513(k) != n, k++); k;} \\ Michel Marcus, Jun 09 2018

Extensions

More terms from David Wasserman, Dec 20 2002