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.

A066190 Numbers k such that the sum of the even aliquot parts of k divides k.

Original entry on oeis.org

4, 6, 10, 12, 14, 22, 26, 34, 38, 46, 56, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478, 482, 502
Offset: 1

Views

Author

Robert G. Wilson v, Dec 15 2001

Keywords

Crossrefs

Union of A100484 and A139256.
Cf. A053813.

Programs

  • Mathematica
    Do[ d = Drop[ Divisors[ n ], -1 ]; l = Length[ d ]; ev = 0; k = 2; While[ k <= l, If[ EvenQ[ d[ [ k ] ] ], ev = ev + d[ [ k ] ] ]; k++ ]; If[ IntegerQ[ n/ev ], Print[ n ] ], {n, 2, 10^3, 2} ]
    Select[Range[550],Divisible[#,Total[Select[Most[Divisors[#]],EvenQ]]]&]//Quiet  (* Harvey P. Dale, Mar 11 2011 *)
  • PARI
    { n=0; for (m=1, 10^9, d=divisors(m); s=0; for (i=2, numdiv(m) - 1, if (d[i]%2 == 0, s += d[i])); if (s > 0 && m%s == 0, write("b066190.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 05 2010

Formula

a(n) = 2*A053813(n). - Amiram Eldar, Jul 07 2022

Extensions

a(56) from Harry J. Smith, Feb 05 2010