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.

A192271 Anti-weird numbers.

Original entry on oeis.org

11, 12, 13, 14, 15, 18, 20, 21, 25, 27, 28, 30, 37, 40, 42, 43, 46, 47, 48, 50, 55, 57, 58, 62, 65, 66, 75, 78, 80, 84, 86, 87, 90, 91, 92, 93, 97, 99, 100, 107, 111, 113, 118, 119, 120, 121, 124, 125, 126, 128, 132, 133, 135, 136, 140, 142, 145, 152, 153, 155, 160, 161, 163, 168, 170, 173, 177, 180, 181, 183, 184, 186, 188, 190, 192, 196, 197, 198, 204, 205, 208, 210, 212, 213, 218, 222, 223
Offset: 1

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Author

Paolo P. Lava, Jun 28 2011

Keywords

Comments

Like A006037 but using anti-divisors: Anti-weird numbers are anti-abundant (A192268) but not pseudo anti-perfect (A192270).

Examples

			25 is an anti-weird number because it is anti-abundant (its anti-divisors are 2, 3, 7, 10, 17 and their sum is 39 > 25) and no subsets of its anti-divisors add up to 25.
		

Crossrefs

Programs

  • Maple
    # see A066272
    isA192270 := proc(n) local a,S ; a := antidivisors(n) ;  S := combinat[subsets](a) ; while not S[finished] do if convert(S[nextvalue](),`+`) = n then return true; end if; end do; false ; end proc:
    isA192268 := proc(n) A066417(n) > n ; end proc:
    isA192271 := proc(n) isA192268(n) and not isA192270(n) ; end proc:
    for n from 1 to 40 do if isA192271(n) then printf("%d,",n) ; end if; end do: # R. J. Mathar, Jul 04 2011