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 A283471 #12 Mar 19 2017 01:08:56 %S A283471 3,4,6,7,8,10,13,14,15,16,18,28,29,30,31,32,34,59,60,61,62,63,64,66, %T A283471 122,123,124,125,126,127,128,130,249,250,251,252,253,254,255,256,258, %U A283471 504,505,506,507,508,509,510,511,512,514,1015,1016,1017,1018,1019,1020,1021,1022,1023,1024,1026,2038,2039,2040,2041,2042,2043,2044,2045 %N A283471 Numbers n > 2 such that A004001(A004001(n-1)) = A004001(n-A004001(n-1)). %C A283471 Equally, numbers n > 2 for which A004001(A004001(n-1)) = A004001(A080677(n-1)). %H A283471 Antti Karttunen, <a href="/A283471/b283471.txt">Table of n, a(n) for n = 1..185</a> %t A283471 a[n_] := a[n] = If[n <= 2, 1, a[a[n - 1]] + a[n - a[n - 1]]]; Select[Range[3, 2^11], Function[n, a[#] == a[n - #] &@ a[n - 1]]] (* _Michael De Vlieger_, Mar 18 2017, after _Robert G. Wilson v_ at A004001 *) %o A283471 (Scheme, with _Antti Karttunen_'s IntSeq-library) %o A283471 (define A283471 (ZERO-POS 1 1 A283470)) %o A283471 (define A283471 (MATCHING-POS 1 3 (lambda (n) (= (A004001 (A004001 (- n 1))) (A004001 (- n (A004001 (- n 1)))))))) %Y A283471 Positions of zeros in A283468 and A283470. %Y A283471 Cf. A004001, A080677, A283473. %Y A283471 Subsequence of A283482. %K A283471 nonn %O A283471 1,1 %A A283471 _Antti Karttunen_, Mar 18 2017