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 A270199 #7 Mar 25 2016 07:47:46 %S A270199 1,3,2,9,6,5,30,15,4,16,12,11,93,45,8,10,46,48,34,33,266,124,26,31, %T A270199 127,23,154,99,97,7,24,727,20,19,352,80,94,357,68,141,69,446,278,272, %U A270199 14,17,70,18,71,73,1902,54,61,52,946,232,267,957,197,408,53,199,1174,763,407,751,186,39,41,47,49,202,50,204,210,4724,164,192,182,36 %N A270199 Self-inverse permutation of natural numbers: a(1) = 1, a(A269389(1+n)) = A269399(a(n)), a(A269399(n)) = A269389(1+a(n)). %H A270199 Antti Karttunen, <a href="/A270199/b270199.txt">Table of n, a(n) for n = 1..4786</a> %H A270199 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A270199 a(1) = 1, for n > 1, if A137264(6+n) = 0 [when n is in A269399], a(n) = A269389(1+a(n-A269362(n))), otherwise a(n) = A269399(a(A269362(n)-1)). %o A270199 (Scheme, with memoization-macro definec) %o A270199 (definec (A270199 n) (cond ((= 1 n) n) ((not (zero? (A137264 (+ 6 n)))) (A269399 (A270199 (+ -1 (A269362 n))))) (else (A269389 (+ 1 (A270199 (- n (A269362 n)))))))) %Y A270199 Cf. A137264, A269362, A269389, A269399. %Y A270199 Related or similar permutations: A267107, A270193, A270194. %K A270199 nonn %O A270199 1,2 %A A270199 _Antti Karttunen_, Mar 16 2016