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 A090548 #12 Sep 24 2018 16:53:14 %S A090548 1,3,7,23,29,157,215,1139,1211,2089,5161,5293,6347,10717,14233,28213, %T A090548 31451,72965,119029,121603,124177,611261,632171,2003171,2012771 %N A090548 Least number that ends an arithmetic progression of n numbers with the same number of divisors. %C A090548 In the following triangle the n-th row contains the least set of n numbers in arithmetic progression with the same number of divisors. By "least" we mean that the largest term is minimized. Sequence contains the leading diagonal. In other words, largest of n numbers in arithmetic progression with the same tau function, or 0 if no such number exists. %F A090548 a(n)=A090547(n)+(n-1)*A090549(n). - _R. J. Mathar_, Apr 28 2007 %e A090548 Triangle (A113470) begins: %e A090548 1 %e A090548 2 3 %e A090548 3 5 7 %e A090548 5 11 17 23 %e A090548 5 11 17 23 29 ... %Y A090548 Leading diagonal of A113470. %Y A090548 Cf. A087309, A096003, A113470, A087308, A090547, A090549. %K A090548 nonn %O A090548 1,2 %A A090548 _Amarnath Murthy_, Dec 09 2003 %E A090548 Corrected and extended by _R. J. Mathar_, Apr 28 2007 %E A090548 More terms from _David Wasserman_, Jan 08 2006, May 11 2007 %E A090548 Edited by _N. J. A. Sloane_ at the suggestion of _Andrew S. Plewe_, May 11 2007