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 A114991 #18 Sep 10 2024 04:30:58 %S A114991 31,61,151,181,241,271,541,601,751,811,1201,1621,1801,2161,2251,3001, %T A114991 4051,4801,4861,6481,7681,8101,8641,9001,9601,9721,11251,14401,15361, %U A114991 19441,21601,21871,22501,23041,24001,32401,33751,36451,37501,43201,54001,57601,58321 %N A114991 Primes of the form 2^a * 3^b * 5^c + 1 for positive a, b, c. %H A114991 T. D. Noe, <a href="/A114991/b114991.txt">Table of n, a(n) for n=1..1000</a> %e A114991 a(1) = 31 = 2^1 * 3^1 * 5^1 + 1. %e A114991 a(2) = 61 = 2^2 * 3^1 * 5^1 + 1. %e A114991 a(3) = 151 = 2^1 * 3^1 * 5^2 + 1. %e A114991 a(4) = 181 = 2^2 * 3^2 * 5^1 + 1. %e A114991 Values include 30000001 = 2^7 * 3^1 * 5^7 + 1, 90000000001 = 2^9 * 3^2 * 5^9 + 1. %Y A114991 Cf. A000040, A005109, A030430. %Y A114991 Cf. A143207. %K A114991 easy,nonn %O A114991 1,1 %A A114991 _Jonathan Vos Post_, Feb 22 2006