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 A221942 #17 Mar 09 2025 11:11:01 %S A221942 2,3,4,6,8,12,17,25,35,50,71,101,143,202,286,404,572,809,1144,1619, %T A221942 2289,3238,4579,6476,9158,12952,18317,25905,36635,51810,73271,103621, %U A221942 146542,207243,293085,414486,586171,828972,1172343,1657944,2344687,3315888,4689374,6631776,9378748,13263553,18757497,26527107 %N A221942 a(n) = floor(sqrt(5*2^n)). %C A221942 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 A221942 Artūras Dubickas, Prime and composite integers close to powers of a number, Monatsh. Math. 158:3 (2009), pp. 271-284. %H A221942 Harvey P. Dale, <a href="/A221942/b221942.txt">Table of n, a(n) for n = 0..1000</a> %t A221942 Floor[Sqrt[5*2^Range[0,50]]] (* _Harvey P. Dale_, Mar 09 2025 *) %o A221942 (PARI) a(n)=sqrtint(5*2^n) \\ _Charles R Greathouse IV_, Apr 18 2013 %Y A221942 Cf. A017910, A017913, A017919, A114183, A221718, A221942-A221946. %K A221942 nonn %O A221942 0,1 %A A221942 _N. J. A. Sloane_, Feb 01 2013