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 A144326 #3 Mar 31 2012 10:28:53 %S A144326 67,191,197,211,277,331,379,397,401,541,617,631,677,727,743,751,821, %T A144326 937,947,971,991,1129,1163,1171,1217,1277,1289,1327,1381,1409,1427, %U A144326 1471,1549,1559,1597,1601,1607,1783,1801,1831,1871,1901,2011,2017,2081,2111 %N A144326 Prime numbers that cannot be Mersenne prime exponents, by conjecture of A144325. %C A144326 Obviously true for the initial terms! %C A144326 Conjecture: 191, 1217, 1559 and 1901 are not in fact members of this sequence, noting that they are (4, 19) k-figurate numbers; 19 is a member of A138694. Determining whether a Mersenne prime exponent one greater than a (4, 19) k-figurate number exists is sufficient to determine whether these primes are members. %Y A144326 Cf. A000040, A000043, A000668, A144313, A144315, A144325, A138694 %K A144326 easy,nonn %O A144326 1,1 %A A144326 _Reikku Kulon_, Sep 17 2008