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 A174623 #16 Sep 08 2022 08:45:51 %S A174623 25,81,1089,16641,4198401,67125249,17180131329,274878955521, %T A174623 70368760954881,288230377225453569,4611686022722355201, %U A174623 18889465931753458761729,4835703278462914745335809,77371252455353859367239681,19807040628566365873362698241 %N A174623 (2^p+1)^2 where p is prime. %H A174623 Vincenzo Librandi, <a href="/A174623/b174623.txt">Table of n, a(n) for n = 1..200</a> %F A174623 a(n) = (A098640(n))^2. - _R. J. Mathar_, Jul 06 2010 %e A174623 For p=2, (2^2+1)^2=25; %e A174623 for p=3, (2^3+1)^2=81; %e A174623 for p=5, (2^5+1)^2=1089. %p A174623 A174623:=n->(2^ithprime(n)+1)^2: seq(A174623(n), n=1..20); # _Wesley Ivan Hurt_, Apr 18 2017 %t A174623 Table[(2^Prime[n] + 1)^2, {n, 30}] (* _Vincenzo Librandi_, Apr 29 2014 *) %o A174623 (Magma) [(2^p+1)^2: p in [0..1000] |IsPrime(p)] %K A174623 nonn %O A174623 1,1 %A A174623 _Vincenzo Librandi_, Apr 11 2010 %E A174623 Definition clarified by _Jon E. Schoenfield_, Jun 18 2010