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.

A200090 Numbers k such that the sum of the distinct prime divisors of k equals three times the largest prime divisor of k.

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%I A200090 #23 May 14 2023 06:57:07
%S A200090 15015,45045,51051,62985,72930,74613,75075,105105,106590,135135,
%T A200090 145860,153153,156009,165165,187473,188955,190190,195195,213180,
%U A200090 218790,222870,223839,225225,279565,291720,314925,315315,319770,335478,357357,364650,375375,380380
%N A200090 Numbers k such that the sum of the distinct prime divisors of k equals three times the largest prime divisor of k.
%H A200090 Amiram Eldar, <a href="/A200090/b200090.txt">Table of n, a(n) for n = 1..10000</a>
%e A200090 15015 is a term because its distinct prime divisors are 3, 5, 7, 11, 13 and their sum 3 + 5 + 7 + 11 + 13 = 39 equals 3*13.
%t A200090 Select[Range[400000],Plus@@(pl=First/@FactorInteger[#])==3*pl[[-1]]&]
%Y A200090 Cf. A006530 (gpf), A008472 (sopf), A200070.
%K A200090 nonn
%O A200090 1,1
%A A200090 _Michel Lagneau_, Nov 13 2011