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.

A036345 Divisible by its 'even' sum of prime factors (counted with multiplicity).

This page as a plain text file.
%I A036345 #24 Feb 18 2019 08:07:12
%S A036345 2,4,16,30,60,70,72,84,220,240,256,286,288,308,378,440,450,476,528,
%T A036345 540,560,576,594,624,646,648,728,800,884,900,960,1040,1056,1080,1160,
%U A036345 1170,1248,1276,1404,1456,1496,1530,1748,1776,1798,1824,1976,2322,2408,2464
%N A036345 Divisible by its 'even' sum of prime factors (counted with multiplicity).
%H A036345 David A. Corneth, <a href="/A036345/b036345.txt">Table of n, a(n) for n = 1..10000</a> (terms a(n) for n = 2..1002 from Harvey P. Dale).
%e A036345 646 = 2*17*19 so the sum of prime factors (with multiplicity) is 2+17+19 = 38 which is even and a divisor of 646 so 646 is in the sequence.
%t A036345 dspfQ[n_]:=Module[{spf=Total[Times@@@FactorInteger[n]]},EvenQ[spf] && Divisible[n,spf]]; Select[Range[4,2500,2],dspfQ] (* _Harvey P. Dale_, Oct 06 2011 *)
%o A036345 (PARI) is(n) = my(f = factor(n), s = sum(i = 1, #f~, f[i, 1] * f[i, 2])); s > 0 && s % 2 == 0 && n % s == 0 \\ _David A. Corneth_, Feb 07 2019
%Y A036345 Cf. A036346, A046346.
%K A036345 nonn
%O A036345 1,1
%A A036345 _Patrick De Geest_, Dec 15 1998
%E A036345 Offset corrected and a(1) = 2 added by _Thomas Ordowski_, Feb 07 2019