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.

A225417 Composite numbers which contain their sum of aliquot parts as a substring.

This page as a plain text file.
%I A225417 #15 Dec 18 2013 19:58:22
%S A225417 6,28,121,437,496,611,1331,1397,8128,10201,14641,27019,40301,40991,
%T A225417 41347,41917,45743,47873,49901,51101,67997,76459,97637,99101,99553,
%U A225417 99779,120353,133307,133961,134179,153091,161051,165101,165743,166171,182525,186503
%N A225417 Composite numbers which contain their sum of aliquot parts as a substring.
%C A225417 A(n) is odd deficient or perfect (A000396).
%C A225417 If definition had not excluded prime numbers, then terms of A208270 would have been included. - _Michel Marcus_, Dec 18 2013
%H A225417 Donovan Johnson, <a href="/A225417/b225417.txt">Table of n, a(n) for n = 1..1000</a>
%e A225417 1031311 is in the sequence because 1031311=10211*101, Sum of aliquot parts: 1+101+10211=10313, substring of 1031311.
%o A225417 (PARI) indigit(a,b)={ u=Vec(Str(a));v=Vec(Str(b));indi=0;la=#u;lb=#v;i=1;while(i<=la-lb+1&&indi==0,d=0;for(x=1,lb,if(v[x]==u[i+x-1],d+=1));indi=(d==lb) ;i+=1);return(indi)}
%o A225417 {for(i=1,10^7,k=sigma(i,1)-i;if(indigit(i,k)&&isprime(i)==0,print(i)))}
%K A225417 nonn,base
%O A225417 1,1
%A A225417 _Antonio Roldán_, May 07 2013