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 A163913 #3 Jul 12 2012 00:39:50 %S A163913 0,0,6,3,30,27,162,171,885,987,4839,5502,26436,30216 %N A163913 Number of integers i in range [A000302(n-1)..A024036(n)] of permutation A163355/A163356 with A163915(i)=i, but not A163355(i)=i. %o A163913 (MIT Scheme:) %o A163913 (define (A163913 n) (let ((rp (range-of-n-th-quaternary-forest n))) (let loop ((s 0) (i (car rp))) (cond ((> i (cdr rp)) s) ((and (not (= (A163355 i) i)) (= (A163915 i) i)) (loop (1+ s) (1+ i))) (else (loop s (1+ i))))))) %o A163913 (define (range-of-n-th-quaternary-forest n) (if (zero? n) (cons n n) (cons (A000302 (-1+ n)) (+ (A000302 (-1+ n)) (-1+ (A002001 n)))))) %Y A163913 a(n) = 3*A163914(n). See also A163903. %K A163913 nonn %O A163913 0,3 %A A163913 _Antti Karttunen_, Sep 19 2009