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 A349820 #19 Jul 09 2022 12:22:24 %S A349820 5,7,11,19,31,47,79,103,191,239,383,479,863,991,2687,2879,3391,4799, %T A349820 6719,9343,21503,23039,36607,69119,72959,126719,152063,382463,602111, %U A349820 927743,972799,1096703,1102847,1640447,1655807,1966079,3565567,3590143,4124671,5402623 %N A349820 Primes p such that 2*p is a member of A230624. %C A349820 It is not known if A230624 is infinite. Many of its initial terms are twice primes, so it would interesting if these primes could be characterized in some other way. %C A349820 a(n)+1 typically has a slowly growing power of 2 as factor. as can be seen here: (PARI) for(k=1, #a, print1(valuation(a[k]+1,2),", ")): 1, 3, 2, 2, 5, 4, 4, 3, 6, 4, 7, 5, 5, 5, 7, 6, 6, 6, 6, 7, 10, 9, 8, 9, 8, 8, 9, 9, 12, 11, 11, 10, 10, 11, 10, 17, 11, 11, 12, 12,.. - _Hugo Pfoertner_ Jan 03 2022 %Y A349820 Cf. A230624, A349821. %K A349820 nonn %O A349820 1,1 %A A349820 _N. J. A. Sloane_, Dec 30 2021 %E A349820 a(29)-a(40) from _Martin Ehrenstein_, Jan 03 2022