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 A099202 #23 May 10 2025 09:16:27 %S A099202 1,1,4,16,256,4096,262144,16777216,4294967296,1099511627776, %T A099202 1125899906842624,1152921504606846976,4722366482869645213696, %U A099202 19342813113834066795298816,316912650057057350374175801344,5192296858534827628530496329220096,340282366920938463463374607431768211456 %N A099202 a(n) = 2^floor(n^2/2). %C A099202 Hankel transform of A168490. Linked to elliptic curve y^2 = 1-12*x+44*x^2-48*x^3 through g.f. of A168490. - _Paul Barry_, Nov 27 2009 %H A099202 Vincenzo Librandi, <a href="/A099202/b099202.txt">Table of n, a(n) for n = 0..80</a> %F A099202 a(n) = A016116(n) * A006125(n) %F A099202 a(n) = 16*a(n-2)^2 / a(n-4). - _Michael Somos_, Sep 16 2005 %F A099202 a(n) = 4^floor(n^2/4) = 4^A002620(n). - _Paul Barry_, Nov 27 2009 %o A099202 (PARI) a(n)=2^(n^2\2) %o A099202 (Magma) [2^Floor(n^2/2): n in [0..20]]; // _Vincenzo Librandi_, Aug 16 2011 %o A099202 (Python) %o A099202 def A099202(n): return 1<<(n**2>>1) # _Chai Wah Wu_, Jan 18 2023 %Y A099202 Cf. A002620, A006125, A016116, A168490. %K A099202 easy,nonn %O A099202 0,3 %A A099202 _Paul Barry_, Oct 04 2004