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 A334950 #47 May 26 2020 06:31:29 %S A334950 0,0,-1,1,-1,3,0,6,2,2,-3,7,1,13,6,20,12,12,3,21,11,11,0,22,10,10,-3, %T A334950 23,9,9,-6,24,8,8,-9,25,7,43,24,62,42,42,21,63,41,41,18,18,-6,42,17, %U A334950 17,-9,43,16,16,-12,44,15,15,-15,45,14,14,-18,46,13,79,45,113,78,78,42,114,77,77,39,39,0,78 %N A334950 Pairs (a,b) where "a" is the smallest candidate for the n-th term of Recamán's sequence and "b" is the n-th term of Recamán's sequence (A005132). %C A334950 For n > 0 and after A005132(n-1) the algorithm of Recamán's sequence first explores if A005132(n-1) - n = A334951(n) is a valid number to be its n-th term. If A334951(n) is nonnegative and not already in Recamán's sequence then it is accepted, so A005132(n) = A334951(n), otherwise A334951(n) is rejected and A005132(n) = A005132(n-1) + n, not A334951(n). This sequence lists the pairs [A334951(n), A005132(n)], with a(0) = 0. %H A334950 <a href="/index/Rea#Recaman">Index entries for sequences related to Recamán's sequence</a> %F A334950 a(2n) = A334951(n). %F A334950 a(2n+1) = A005132(n). %e A334950 Illustration of initial terms: %e A334950 23 %e A334950 22 _ %e A334950 21 _ | %e A334950 20 _ | | | %e A334950 _ | | | | | %e A334950 | | | | | | | %e A334950 | | | | | | | %e A334950 | | | | | | | %e A334950 | | | | | | | %e A334950 | | | | | | | %e A334950 13 | | | | | | | %e A334950 _ | | 12 | | | | | %e A334950 | | | |_ _ | | 11 | | | %e A334950 | | | | | |_ _ | | 10 | %e A334950 | | | 12 | | | | |_ _ | %e A334950 | | | | | 11 | | | | %e A334950 7 | | | | | | | 10 | | %e A334950 6 _ | | | | | | | | | %e A334950 _ | | | |_| | | | | | | %e A334950 | | | | | | | | | | | %e A334950 3 | | | | | 6 | | | | | | %e A334950 _ | | 2 | | | |_| | | | | %e A334950 1 | | | |_ _ | | | | | | | %e A334950 0 _ | | | | | |_| 3 | | | | %e A334950 _ _ | | | |_| 2 | | |_| | | %e A334950 |_| |_| | | 1 | | %e A334950 0 0 | | 0 | | %e A334950 -1 -1 |_| |_| %e A334950 . %e A334950 -3 -3 %e A334950 . %e A334950 In the above diagram the numbers that are written below the path are the terms of A334951 (the candidates for A005132). The numbers that are written above the path are the terms of Recamán's sequence A005132. The length of the n-th vertical-line-segment equals the absolute value of A334952(n). %e A334950 For n = 4, after A005132(4-1) = 6 the algorithm of Recamán's sequence first explores if A334951(4) = 6 - 4 = 2 is a valid number to be its 4th term. We can see that 2 is nonnegative and not already in Recamán's sequence, then it is accepted, so A005132(4) = A334951(4) = 2. %e A334950 For n = 5, after A005132(5-1) = 2 the algorithm first explores if A334951(5) = 2 - 5 = -3 is a valid number to be its 5th term. We can see that -3 is negative, so -3 is rejected. %e A334950 For n = 6, after A005132(6-1) = 7 the algorithm first explores if A334951(6) = 7 - 6 = 1 is a valid number to be its 6th term. We can see that 1 is already in Recamán's sequence, so 1 is rejected. %Y A334950 Cf. A334951 and A005132 interleaved. %Y A334950 Cf. A334952 (first differences). %K A334950 sign %O A334950 0,6 %A A334950 _Omar E. Pol_, May 17 2020