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 A082426 #19 May 09 2025 03:04:28 %S A082426 1,3,10,49,301,2161,17641,161281,1632961,18144001,219542401, %T A082426 2874009601,40475635201,610248038401,9807557760001,167382319104001, %U A082426 3023343138816001,57621363351552001,1155628453883904001,24329020081766400001,536454892802949120001,12364008005553684480001 %N A082426 a(n) = floor(n*n!/2 + 1). %C A082426 Concatenate all the permutations of 1..n in lexicographical order. a(n) is the number of ascending runs. - _David Scambler_, May 26 2011 %F A082426 a(n) = A074143(n) + 1 for n >= 2. - _Georg Fischer_, May 15 2024 %p A082426 seq(floor(n*n!/2 + 1), n=1..20); %t A082426 a[n_] := Floor[n*n!/2 + 1]; Array[a, 20] (* _Amiram Eldar_, May 09 2025 *) %o A082426 (PARI) a(n) = (n*n!)\2 + 1; \\ _Amiram Eldar_, May 09 2025 %Y A082426 Cf. A074143. %K A082426 nonn,easy %O A082426 1,2 %A A082426 _Benoit Cloitre_, Apr 24 2003 %E A082426 Definition corrected by _Georg Fischer_, May 15 2024