A066193 Composite numbers k such that the difference between the odd and even aliquot parts of k divides k.

4, 6, 20, 30, 60, 270, 630, 728, 1170, 1638, 1890, 2310, 2730, 2970, 4590, 8190, 8910, 12870, 14850, 16830, 17850, 18018, 18810, 19110, 19890, 22230, 27846, 27930, 33930, 52290, 56070, 60512, 61110, 63630, 64890, 67410, 68670, 80730, 86130

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..290

Mathematica

Do[ d = Drop[ Divisors[ n ], -1 ]; l = Length[ d ]; ev = 0; od = 1; k = 2; While[ k <= l, If[ EvenQ[ d[ [ k ] ] ], ev = ev + d[ [ k ] ], od = od + d[ [ k ] ] ]; k++ ]; If[ !PrimeQ[ n ] && IntegerQ[ n/ Abs[ ev - od ] ], Print[ n ] ], {n, 2, 10^5} ]

Prog

(PARI) { n=0; for (m=4, 10^9, if (isprime(m), next); d=divisors(m); s=1; for (i=2, numdiv(m) - 1, if (d[i]%2, s += d[i], s -= d[i])); if (s != 0 && m%s == 0, write("b066193.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 05 2010

Crossrefs

Sequence in context: A205955 A023863 A024480 * A026711 A273995 A026788

Adjacent sequences: A066190 A066191 A066192 * A066194 A066195 A066196

Keyword

nonn

Author

Robert G. Wilson v, Dec 15 2001

Status

approved