A341274 Composite numbers k that are divisible by (k mod sopfr(k))+floor(k/sopfr(k)), where sopfr = A001414.

4, 6, 12, 16, 20, 21, 24, 27, 30, 36, 40, 45, 48, 52, 56, 60, 66, 70, 72, 75, 80, 84, 88, 90, 96, 105, 108, 112, 117, 126, 140, 150, 152, 160, 180, 182, 192, 195, 198, 200, 220, 224, 225, 231, 240, 252, 255, 256, 270, 286, 288, 290, 301, 306, 308, 320, 330, 344, 345, 352, 360, 378, 384, 396, 429

Offset

1,1

Links

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

Example

a(5) = 20 is a term because sopfr(20) = 2*2+5 = 9, and 20 is divisible by (20 mod 9)+floor(20/9) = 4.

Maple

spf:= proc(n) local t; add(t[1]*t[2], t=ifactors(n)[2]) end proc:
filter:= proc(n) local s, m;
  if isprime(n) then return false fi;
  s:= spf(n);
  m:= n mod s;
  n mod (m + (n-m)/s) = 0
end proc:
select(filter, [$4..500]);

Crossrefs

Contains A190275.

Cf. A001414.

Sequence in context: A265225 A122781 A153355 * A361795 A310597 A310598

Adjacent sequences: A341271 A341272 A341273 * A341275 A341276 A341277

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Feb 08 2021

Status

approved