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 A056200 #18 Aug 18 2024 05:17:04 %S A056200 1,1,4,5,26,22,120,149,418,716,2036,2378,8178,12846,29294,50709, %T A056200 131054,193972,524268,843260,1979520,3488618,8388584,13190042, %U A056200 33501276,56707912,129527950,227113934,536870882,887838482,2147483616,3683332117,8396392382,14846262368,34352689180 %N A056200 a(n) = 2^n - A056045(n). %H A056200 Amiram Eldar, <a href="/A056200/b056200.txt">Table of n, a(n) for n = 1..1000</a> %F A056200 a(p) = 2^p - p - 1 for a prime p. %t A056200 a[n_] := 2^n - DivisorSum[n, Binomial[n, #] &]; Array[a, 40] (* _Amiram Eldar_, Aug 18 2024 *) %o A056200 (PARI) a(n) = 2^n - sumdiv(n, d, binomial(n, d)); \\ _Michel Marcus_, Aug 25 2019 %Y A056200 Cf. A000079, A056045. %K A056200 nonn %O A056200 1,3 %A A056200 _Labos Elemer_, Aug 02 2000 %E A056200 More terms from _Amiram Eldar_, Aug 18 2024