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 A069614 #19 May 21 2025 18:56:57 %S A069614 2,23,223,2237,32237,3223729,63223729,632237297,2632237297, %T A069614 263223729721,12263223729721,1226322372972173,171226322372972173, %U A069614 17122632237297217381,2117122632237297217381,21171226322372972173813 %N A069614 a(1) = 2; a(2n) = smallest prime starting (the most significant digits) with a(2n-1) (i.e., as a right concatenation of a(2n-1) and a number with no insignificant zeros); a(2n+1) = smallest prime ending in (the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes. %e A069614 a(4) = 2111 starting with a(3) = 211 and a(5) = 22111 ending in a(4) = 2111. %Y A069614 Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613. %K A069614 nonn,base %O A069614 1,1 %A A069614 _Amarnath Murthy_, Mar 27 2002 %E A069614 More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003