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.

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%I A066190 #17 Jul 07 2022 08:11:50
%S A066190 4,6,10,12,14,22,26,34,38,46,56,58,62,74,82,86,94,106,118,122,134,142,
%T A066190 146,158,166,178,194,202,206,214,218,226,254,262,274,278,298,302,314,
%U A066190 326,334,346,358,362,382,386,394,398,422,446,454,458,466,478,482,502
%N A066190 Numbers k such that the sum of the even aliquot parts of k divides k.
%H A066190 Harry J. Smith, <a href="/A066190/b066190.txt">Table of n, a(n) for n = 1..1000</a>
%F A066190 a(n) = 2*A053813(n). - _Amiram Eldar_, Jul 07 2022
%t A066190 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} ]
%t A066190 Select[Range[550],Divisible[#,Total[Select[Most[Divisors[#]],EvenQ]]]&]//Quiet  (* _Harvey P. Dale_, Mar 11 2011 *)
%o A066190 (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
%Y A066190 Union of A100484 and A139256.
%Y A066190 Cf. A053813.
%K A066190 nonn
%O A066190 1,1
%A A066190 _Robert G. Wilson v_, Dec 15 2001
%E A066190 a(56) from _Harry J. Smith_, Feb 05 2010