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.
%I A087238 #12 Sep 01 2018 17:44:10 %S A087238 2,2,2,19,3,3,63,4,20,210,5,5,10,5,5,648,72,12,24,6,6,6,1925,7,7,7,7, %T A087238 7,5314,16,16,16,8,8,15054,9,765,40240,40,30,10,30,40,10,10,10,110477, %U A087238 305655,12,144,12,12,12,12,12,12,12,204,60,12,36,12,12,12,12,823046,13 %N A087238 First differences of A057809. %H A087238 Giovanni Resta, <a href="/A087238/b087238.txt">Table of n, a(n) for n = 2..1161</a> %F A087238 a(n)=A057809(n+1)-A057809(n) %e A087238 Large differences arise between max term in a cluster and least one in the next cluster of A057809. While small entries obtained as differences inside a cluster. %e A087238 E.g.:...,21,6467079011,198,22,110,132,22,242,66,17541629593,23,... shows by first differences the transition from the 21st cluster to 23rd solution-set over the 22nd-set with multiples of 22. %e A087238 First cluster is empty, while 11th contains one term (see A038227). %t A087238 Differences[Select[Range[2,1500000],Divisible[#,PrimePi[#]]&]] (* _Harvey P. Dale_, Aug 13 2012 *) %Y A087238 Cf. A038623-A038627, A057809, A087235-A087242. %K A087238 nonn %O A087238 2,1 %A A087238 _Labos Elemer_, Sep 04 2003