cp's OEIS Frontend

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.

A352750 a(n) = binary complement of b(n-1) AND b(n); a(1) = 1, where b(n) = A109812(n).

This page as a plain text file.
%I A352750 #13 Apr 05 2022 21:03:01
%S A352750 1,0,1,0,4,2,0,5,9,0,4,1,2,0,17,24,0,6,10,0,16,8,4,2,8,16,2,0,48,41,0,
%T A352750 20,36,0,24,36,0,18,32,8,4,32,24,0,32,16,3,8,0,39,98,0,28,96,0,28,80,
%U A352750 0,41,81,16,8,4,2,1,4,8,1,0,48,68,0,48,64,3,32,64
%N A352750 a(n) = binary complement of b(n-1) AND b(n); a(1) = 1, where b(n) = A109812(n).
%C A352750 b(n) = A109812(n) is the least k that does not appear in b(1..n-1) that avoids the ON bits in b(n-1).
%C A352750 a(n) is the decimal value of available bits "unused" in k.
%C A352750 If b(n) = 2^m - 1, then a(n) = 0 iff b(n) = 2^m.
%H A352750 Rémy Sigrist, <a href="/A352750/b352750.txt">Table of n, a(n) for n = 1..10000</a>
%H A352750 Michael De Vlieger, <a href="/A352750/a352750.png">Log-log scatterplot of a(n)</a> for n = 1..2^16, substituting 1/2 for 0 so as to plot in blue, records labelled in red, fixed points shown in amber.
%H A352750 Michael De Vlieger, <a href="/A352750/a352750_1.png">Bitmap of a(n)</a> for n = 1..2^10, where each term is shown vertically, with least significant bit at bottom, 12X vertical exaggeration. Black corresponds to 1 and white to 0.
%H A352750 Michael De Vlieger, <a href="/A352750/a352750_2.png">Bitmap of a(n)</a> for n = 1..2^14, where each term is shown horizontally, with least significant bit at right, 256X horizontal exaggeration. Black corresponds to 1 and white to 0.
%H A352750 Rémy Sigrist, <a href="/A352750/a352750.gp.txt">PARI program</a>
%F A352750 a(n) = 2^(1 + max(floor(log_2 i), floor(log_2 j))) - (i + j) - 1, with i = A109812(n-1) and j = A109812(n). - _Michael De Vlieger_, Apr 05 2022
%e A352750 Relation between a(n) and b(n) = A109812(n). The binary expansion of b(n) = b(n)_2 = A352575(n), showing zeros as "." to accentuate 1 bits:
%e A352750 n    b(n)_2  b(n) a(n)
%e A352750 ----------------------
%e A352750 1         1    1    1
%e A352750 2        1.    2    0
%e A352750 3       1..    4    1
%e A352750 4        11    3    0
%e A352750 5      1...    8    4
%e A352750 6       1.1    5    2
%e A352750 7      1.1.   10    0
%e A352750 8     1....   16    5
%e A352750 9       11.    6    9
%e A352750 10     1..1    9    0
%e A352750 11    1..1.   18    4
%e A352750 12     11..   12    1
%e A352750 13    1...1   17    2
%e A352750 14     111.   14    0
%e A352750 15   1.....   32   17
%e A352750 16      111    7   24
%e A352750 ...
%t A352750 c[_] = 0; a[1] = c[1] = 1; u = 2; {1}~Join~Reap[Do[k = u; While[Nand[c[k] == 0, BitAnd[a[i - 1], k] == 0], k++]; Set[{a[i], c[k]}, {k, i}]; Sow[FromDigits[IntegerDigits[BitOr[a[i - 1], a[i]], 2] /. {0 -> 1, 1 -> 0}, 2]]; If[k == u, While[c[u] > 0, u++]], {i, 2, 77}]][[-1, -1]]
%o A352750 (PARI) See Links section.
%Y A352750 Cf. A109812, A352575.
%K A352750 nonn,look
%O A352750 1,5
%A A352750 _Michael De Vlieger_, Apr 01 2022