A075558 a(n) is the least composite number that has not yet appeared such that the n-th partial sum is a multiple of the n-th prime.

4, 8, 18, 12, 24, 25, 28, 14, 51, 48, 16, 85, 36, 104, 44, 66, 125, 146, 84, 56, 174, 96, 64, 185, 39, 165, 34, 68, 143, 72, 252, 203, 114, 38, 190, 189, 120, 446, 88, 132, 490, 410, 69, 50, 100, 249, 312, 535, 108, 54, 341, 168, 297, 290, 688, 186, 455, 335, 198, 413

Offset

1,1

Links

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

Maple

s:= 0: Cands:= remove(isprime, [$4..1000]): nC:= nops(Cands):
R:= NULL: s:= 0: p:= 1:
for n from 1 do
  p:= nextprime(p);
  found:= false;
  for i from 1 to nC do
    if s + Cands[i] mod p = 0 then
       R:= R, Cands[i];
       s:= s + Cands[i];
       Cands:= subsop(i=NULL, Cands);
       nC:= nC-1;
       found:= true;
       break
     fi
  od;
  if not found then break fi
od:
R;

Crossrefs

Cf. A002808 (composite numbers).

Sequence in context: A145779 A252790 A144178 * A312824 A312825 A312826

Adjacent sequences: A075555 A075556 A075557 * A075559 A075560 A075561

Keyword

nonn,look

Author

Amarnath Murthy, Sep 24 2002

Extensions

More terms from Ray Chandler, Oct 25 2003

Name changed by Robert Israel, Dec 07 2024

Status

approved