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 A172488 #5 Jun 02 2025 02:24:07 %S A172488 12289,18433,139969,209953,472393 %N A172488 Primes of the form 2^i * 3^j + 1 with i + j = 13. %C A172488 Note that bases 2 = prime(1), 3 = prime(2) %C A172488 13 = prime(prime(1) * prime(2)) %C A172488 A finite "FUN" sequence with 5 = prime(3) terms %D A172488 E. I. Ignatjew, Mathematische Spielereien, Urania Verlag Leipzig/Jena/Berlin 1982 %D A172488 Helmut Kracke, Mathe-musische Knobelisken, Duemmler Bonn, 2. Auflage 1983 %e A172488 12289 = 2^12 * 3^1 + 1 = prime(1470) = prime(2 * 3 * 5 * 7^2) %e A172488 18433 = 2^11 * 3^2 + 1 = prime(2111), index is prime(318) %e A172488 139969 = 2^6 * 3^7 + 1 = prime(13006), larger of a Prime Twin Couple: PTC(1608) %e A172488 209953 = 2^5 * 3^8 + 1 = prime(18802) %e A172488 472393 = 2^3 * 3^10 + 1 = prime(39420) %Y A172488 A172315, A005105 %K A172488 fini,full,nonn %O A172488 1,1 %A A172488 Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Feb 05 2010