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 A306185 #13 Oct 26 2024 21:17:49 %S A306185 5,23,153,1329,14235,181215,2672145,44781345,840523635,17465201775, %T A306185 397983749625,9867844134225,264469801070475,7618612476650175, %U A306185 234748657653134625,7703855828862818625,268263758052098683875,9879138385352252391375,383608053176023482431625,15664153113813817068080625 %N A306185 a(n) = (2n+1)!! + (2n)!! where k!! = A006882(k). %F A306185 a(n) = A006882(2*n+1) + A006882(2*n). %e A306185 a(3) = A006882(7) + A006882(6) = (7*5*3) + (6*4*2) = 105 + 48 = 153. %o A306185 (Python) %o A306185 o=e=1 %o A306185 for n in range(2, 99, 2): %o A306185 o*=n+1 %o A306185 e*=n %o A306185 print(o+e, end=', ') %Y A306185 Cf. A006882, A122649, A129890, A232617, A232618, A306184. %K A306185 nonn %O A306185 1,1 %A A306185 _Alex Ratushnyak_, Jan 27 2019