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.

A175466 Table read by antidiagonals: a(m,n) = the largest positive integer occurring, when written in binary, as a substring in both binary m and binary n.

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%I A175466 #15 Aug 14 2025 04:24:58
%S A175466 1,1,1,1,2,1,1,1,1,1,1,2,3,2,1,1,2,1,1,2,1,1,2,1,4,1,2,1,1,1,3,2,2,3,
%T A175466 1,1,1,2,3,2,5,2,3,2,1,1,2,1,1,2,2,1,1,2,1,1,2,1,4,1,6,1,4,1,2,1,1,2,
%U A175466 1,4,2,3,3,2,4,1,2,1,1,2,3,2,2,2,7,2,2
%N A175466 Table read by antidiagonals: a(m,n) = the largest positive integer occurring, when written in binary, as a substring in both binary m and binary n.
%H A175466 Rémy Sigrist, <a href="/A175466/b175466.txt">Table of n, a(n) for n = 1..11325</a>
%H A175466 Rémy Sigrist, <a href="/A175466/a175466.png">Colored representation of the table for n = 1..1023 and k = 1023</a>
%F A175466 From _Rémy Sigrist_, Jul 20 2019: (Start)
%F A175466 1 <= a(n, k) <= min(n, k).
%F A175466 a(n, k) = a(k, n).
%F A175466 a(n, n) = n.
%F A175466 a(n, 1) = 1.
%F A175466 a(n, 2) = A043529(n).
%F A175466 a(n, 3) = 3 iff n belongs to A004780. (End)
%e A175466 From _Rémy Sigrist_, Jul 20 2019: (Start)
%e A175466 Table a(n, k) begins (in decimal):
%e A175466   n\k|  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15
%e A175466   ---+---------------------------------------------------
%e A175466     1|  1  1  1  1  1  1  1  1  1   1   1   1   1   1   1
%e A175466     2|  1  2  1  2  2  2  1  2  2   2   2   2   2   2   1
%e A175466     3|  1  1  3  1  1  3  3  1  1   1   3   3   3   3   3
%e A175466     4|  1  2  1  4  2  2  1  4  4   2   2   4   2   2   1
%e A175466     5|  1  2  1  2  5  2  1  2  2   5   5   2   5   2   1
%e A175466     6|  1  2  3  2  2  6  3  2  2   2   3   6   6   6   3
%e A175466     7|  1  1  3  1  1  3  7  1  1   1   3   3   3   7   7
%e A175466     8|  1  2  1  4  2  2  1  8  4   2   2   4   2   2   1
%e A175466     9|  1  2  1  4  2  2  1  4  9   2   2   4   2   2   1
%e A175466    10|  1  2  1  2  5  2  1  2  2  10   5   2   5   2   1
%e A175466    11|  1  2  3  2  5  3  3  2  2   5  11   3   5   3   3
%e A175466    12|  1  2  3  4  2  6  3  4  4   2   3  12   6   6   3
%e A175466    13|  1  2  3  2  5  6  3  2  2   5   5   6  13   6   3
%e A175466    14|  1  2  3  2  2  6  7  2  2   2   3   6   6  14   7
%e A175466    15|  1  1  3  1  1  3  7  1  1   1   3   3   3   7  15
%e A175466 Table a(n, k) begins (in binary):
%e A175466    n\k| 1 10 11 100 101 110 111 1000 1001 1010 1011 1100 1101 1110 1111
%e A175466   ----+----------------------------------------------------------------
%e A175466      1| 1  1  1   1   1   1   1    1    1    1    1    1    1    1    1
%e A175466     10| 1 10  1  10  10  10   1   10   10   10   10   10   10   10    1
%e A175466     11| 1  1 11   1   1  11  11    1    1    1   11   11   11   11   11
%e A175466    100| 1 10  1 100  10  10   1  100  100   10   10  100   10   10    1
%e A175466    101| 1 10  1  10 101  10   1   10   10  101  101   10  101   10    1
%e A175466    110| 1 10 11  10  10 110  11   10   10   10   11  110  110  110   11
%e A175466    111| 1  1 11   1   1  11 111    1    1    1   11   11   11  111  111
%e A175466   1000| 1 10  1 100  10  10   1 1000  100   10   10  100   10   10    1
%e A175466   1001| 1 10  1 100  10  10   1  100 1001   10   10  100   10   10    1
%e A175466   1010| 1 10  1  10 101  10   1   10   10 1010  101   10  101   10    1
%e A175466   1011| 1 10 11  10 101  11  11   10   10  101 1011   11  101   11   11
%e A175466   1100| 1 10 11 100  10 110  11  100  100   10   11 1100  110  110   11
%e A175466   1101| 1 10 11  10 101 110  11   10   10  101  101  110 1101  110   11
%e A175466   1110| 1 10 11  10  10 110 111   10   10   10   11  110  110 1110  111
%e A175466   1111| 1  1 11   1   1  11 111    1    1    1   11   11   11  111 1111
%e A175466 (End)
%o A175466 (PARI) sub(n) = { my (b=binary(n), s=[]); for (i=1, #b, if (b[i], for (j=i, #b, s=setunion(s, Set(fromdigits(b[i..j], 2)))))); return (s) }
%o A175466 T(n,k) = my (i=setintersect(sub(n), sub(k))); i[#i] \\ _Rémy Sigrist_, Jul 20 2019
%Y A175466 Cf. A043529, A004780, A175488.
%K A175466 base,nonn,tabl
%O A175466 1,5
%A A175466 _Leroy Quet_, May 24 2010
%E A175466 More terms from _Rémy Sigrist_, Jul 20 2019