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 A221943 #12 Apr 11 2018 10:09:16 %S A221943 2,3,5,7,10,14,21,29,42,59,84,119,169,239,338,478,677,957,1354,1915, %T A221943 2709,3831,5418,7662,10836,15325,21673,30651,43347,61303,86695,122606, %U A221943 173391,245213,346783,490426,693567,980853,1387135,1961706,2774271,3923412,5548542,7846824,11097085,15693648,22194170,31387297 %N A221943 Floor(sqrt(7*2^n)). %C A221943 Theorem 3 of Dubickas implies that infinitely many terms of this sequence are divisible by 2 or 3 (and hence infinitely many composites). - _Charles R Greathouse IV_, Feb 04 2016 %D A221943 Artūras Dubickas, Prime and composite integers close to powers of a number, Monatsh. Math. 158:3 (2009), pp. 271-284. %t A221943 Floor[Sqrt[7*2^Range[0,50]]] (* _Harvey P. Dale_, Apr 11 2018 *) %o A221943 (PARI) a(n)=sqrtint(7<<n) \\ _Charles R Greathouse IV_, Apr 18 2013 %Y A221943 Cf. A017910, A017913, A017919, A114183, A221718, A221942-A221946. %K A221943 nonn %O A221943 0,1 %A A221943 _N. J. A. Sloane_, Feb 01 2013