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 A372944 #7 May 18 2024 01:49:36 %S A372944 1,2,4,8,16,32,64,68,128,256,512,592,1024,1156,2048,2056,4096,4112, %T A372944 8192,8224,8576,10928,16384,16448,19652,20512,28936,32768,37888,41024, %U A372944 43882,64804,65536,82048 %N A372944 Numbers k that divide the k-th tangent (or "zag") number. %C A372944 Numbers k such that k | A000182(k). %C A372944 All the powers of 2 are terms. %e A372944 2 is a term since A000182(2) = 2 is divisible by 2. %e A372944 4 is a term since A000182(4) = 272 = 4 * 68 is divisible by 4. %t A372944 Select[Range[1000], Divisible[((-4)^# - (-16)^#) * BernoulliB[2*#]/(2*#), #] &] %o A372944 (PARI) is(n) = (((-4)^n - (-16)^n) * bernfrac(2*n) / (2*n)) % n == 0; %Y A372944 Cf. A000182. %Y A372944 Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin). %K A372944 nonn,more %O A372944 1,2 %A A372944 _Amiram Eldar_, May 17 2024