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 A285716 #21 Aug 07 2023 11:35:57 %S A285716 0,0,0,0,1,0,0,1,0,0,1,0,1,2,0,0,1,1,0,1,0,0,2,0,1,1,0,1,1,0,0,2,1,0, %T A285716 1,0,0,2,1,0,3,0,1,1,0,1,1,1,0,2,0,0,2,0,0,1,0,1,2,1,1,1,2,0,1,0,1,3, %U A285716 0,0,1,1,1,2,0,0,2,1,0,1,1,0,2,0,1,2,0,2,1,0,0,1,1,1,3,0,0,2,0,0,1,1,1,2,1,0,1,1,1,1,1,0,3,0,0,2,0,1,1,0 %N A285716 a(n) = A080791(A245611(n)). %H A285716 Antti Karttunen, <a href="/A285716/b285716.txt">Table of n, a(n) for n = 1..8192</a> %F A285716 a(1) = 0, a(2) = 1, for n > 2, a(n) = a(A285712(n)) + [n == 2 mod 3]. (Where [] is Iverson bracket, giving here 1 only if n is of the form 3k+2, and 0 otherwise.) %F A285716 a(n) = A080791(A245611(n)). %F A285716 For all n >= 2, a(n) = A091304(n)-1 = A000120(A244153(n))-1. - _Antti Karttunen_, May 31 2017 %t A285716 a[n_] := PrimeOmega[2*n - 1] - 1; a[1] = 0; Array[a, 100] (* _Amiram Eldar_, Jul 23 2023 *) %o A285716 (Scheme) %o A285716 ;; First implementation uses memoization-macro definec: %o A285716 (definec (A285716 n) (if (<= n 2) 0 (+ (if (= 2 (modulo n 3)) 1 0) (A285716 (A285712 n))))) %o A285716 (define (A285716 n) (A080791 (A245611 n))) %Y A285716 One less than A091304 after the initial term. %Y A285716 Cf. A000120, A080791, A244153, A245611, A278223, A285712, A285714, A285715. %Y A285716 Cf. A006254 (gives the positions of zeros after initial a(1)=0.) %K A285716 nonn %O A285716 1,14 %A A285716 _Antti Karttunen_, Apr 25 2017