cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A036346 Composites n such that A001414(n) is odd and divides n.

Original entry on oeis.org

27, 105, 150, 180, 231, 588, 627, 650, 805, 840, 897, 945, 1008, 1100, 1122, 1134, 1581, 1755, 2079, 2106, 2625, 2660, 2800, 2958, 2964, 2967, 2970, 3055, 3125, 3150, 3432, 3564, 3750, 3861, 4000, 4070, 4185, 4500, 4543, 4760, 4800, 5292, 5304, 5355
Offset: 1

Views

Author

Patrick De Geest, Dec 15 1998

Keywords

Examples

			5445 = 3*3*5*11*11 -> sum = 3+3+5+11+11 = 33 (=odd) so 33 divides 5445 exactly.
		

Crossrefs

Programs

  • Maple
    filter:= proc(n) local F,s;
      if isprime(n) then return false fi;
      F:=  ifactors(n)[2];
      s:= add(t[1]*t[2],t=F);
      s::odd and ( n mod s = 0)
    end proc:
    select(filter, [$1..10000]); # Robert Israel, Jul 15 2020
  • Mathematica
    With[{s = Map[{#, Total[Times @@@ FactorInteger[#]]} &, Select[Range[4, 6000], CompositeQ]]}, Select[s, Mod[#1, #2] == 0 && OddQ[#2] & @@ # &][[All, 1]] ] (* Michael De Vlieger, Jul 15 2020 *)

Extensions

Name and offset corrected by Robert Israel, Jul 15 2020
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