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 A089291 #13 Apr 21 2014 10:38:07 %S A089291 101,787,12101,32323,34543,78787,1012321,1212121,3212123,3212323, %T A089291 3454343,7654567,7656787,7676567,7678787,7876567,7898767,101012321, %U A089291 101210101,101232121,121232101,123210121,123232121,321234343,323232323 %N A089291 Prime worms (as defined below). %C A089291 By analogy, primes of this type are worms with a head and tail and body composed of the same digit which weaves in and out of the prime. In a(2)=12101 the worm is defined by the digit 1. %D A089291 The concept is due to Carlos Rivera in his Puzzle 246 (where he asks for the first pandigital prime worm and for the first pandigital titanic prime worm - solutions are at his site). %H A089291 Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_246.htm">Puzzle 246. The worms</a> %F A089291 Primes whose first and last digits are identical and whose successive digit differences have a uniformly absolute value of 1. Thus the sum of absolute values is one less than the number of digits in the prime. No two adjacent digits are identical or differ by more than one. %e A089291 a(2)=12101 because that number is prime with identical first and last digits. Then abs(1-2)=1; abs(2-1)=1; abs(1-0)=1; abs(0-1)=1; and sum of absolute values is 4, one less than the 5 digits in the prime. %Y A089291 This is a subset of A048398. Cf. A089315-A089317, A048398-A048405. %K A089291 nonn,base %O A089291 1,1 %A A089291 _Enoch Haga_, Dec 23 2003 %E A089291 Edited by _Charles R Greathouse IV_, Aug 02 2010