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 A275491 #25 Sep 03 2023 10:45:18 %S A275491 0,0,1,2,7,13,24,48,85,152,276,499,881 %N A275491 Number of primitive weird numbers (A002975) below 10^n. %C A275491 It is not known unconditionally whether there are infinitely many primitive weird numbers (PWN; A002975), although numerical data provides strong evidence: even the number of weird numbers of the form 2^k*p*q (A258882, A258333) seems to increase rapidly as k increases. G. Melfi has shown that Cramer's conjecture implies the infiniteness of PWN. %C A275491 Partial sums of A275492. %H A275491 Giuseppe Melfi, <a href="http://dx.doi.org/10.1016/j.jnt.2014.07.024">On the conditional infiniteness of primitive weird numbers</a>, Journal of Number Theory, Volume 147, February 2015, Pages 508-514. %o A275491 (PARI) my(s=0); vector(10,n,s+=sum(n=10^n\20+1,10^n\2,is_A002975(n*2))) %o A275491 (PARI) vector(10,n,#select(t->t<10^n,A002975)) \\ If A002975 is defined as set, vector, or list with enough terms. %Y A275491 Cf. A002975, A006037, A258333, A258882, A275492, A275493, A275494. %K A275491 nonn,more %O A275491 0,4 %A A275491 _M. F. Hasler_, Jul 30 2016 %E A275491 a(12) from _Robert G. Wilson v_, May 25 2018 %E A275491 a(10) corrected by _Amiram Eldar_, Sep 02 2023