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 A246956 #16 Nov 21 2014 16:30:55
%S A246956 3,10,44,136,592,2144,8384,32896,133376,527872,2102272,8394752,
%T A246956 33624064,134438912,536920064,2147516416,8591835136,34360131584,
%U A246956 137444458496,549759483904,2199041081344,8796124479488,35184409837568,140737849065472,562950540623872,2251800317001728,9007201200898048,36028797421617152,144115191028645888,576460753914036224,2305843021024854016,9223372069067030528
%N A246956 Numbers a(n) = 2^(n-1) * f(n), where n >= 1 and f(n) is the smallest prime number larger than 2^n (A014210).
%C A246956 The sequence is the "diagonal" - first element in each column - of the triangle of numbers associated with the symmetric representation of sigma(n) when it has two parts, each of width one (see A246955).
%H A246956 Jens Kruse Andersen, <a href="/A246956/b246956.txt">Table of n, a(n) for n = 1..1000</a>
%e A246956 a(4) = 8 * 17 = 136 since 17 is the first prime larger than 16.
%t A246956 f[n_] := Module[{v = 2^n + 1}, While[!PrimeQ[v], v++]; v]
%t A246956 a[n_] := 2^(n - 1) f[n]
%t A246956 Map[a,Range[32]] (* data *)
%o A246956 (PARI) a(n) = 2^(n-1) * nextprime(2^n+1); \\ _Michel Marcus_, Sep 23 2014
%Y A246956 Cf. A000203, A014210, A237270, A237271, A237593, A246955.
%K A246956 nonn
%O A246956 1,1
%A A246956 _Hartmut F. W. Hoft_, Sep 08 2014