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.

Showing 1-5 of 5 results.

A352575 A109812(n) in binary.

Original entry on oeis.org

1, 10, 100, 11, 1000, 101, 1010, 10000, 110, 1001, 10010, 1100, 10001, 1110, 100000, 111, 11000, 100001, 10100, 1011, 100100, 10011, 101000, 10101, 100010, 1101, 110000, 1111, 1000000, 10110, 101001, 1000010, 11001, 100110, 1000001, 11010, 100101, 1001000, 10111, 1100000, 11011, 1000100, 100011, 11100, 1000011, 101100, 1010000, 100111, 1011000, 10000000
Offset: 1

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Author

N. J. A. Sloane, Apr 04 2022

Keywords

Crossrefs

Programs

A351963 Lexicographically earliest infinite sequence such that a(i) = a(j) => A278222(A109812(i)) = A278222(A109812(j)), for all i, j >= 1.

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 3, 1, 2, 3, 3, 2, 3, 4, 1, 4, 2, 3, 3, 5, 3, 5, 3, 6, 3, 5, 2, 7, 1, 5, 6, 3, 5, 5, 3, 5, 6, 3, 8, 2, 9, 3, 5, 4, 5, 5, 3, 8, 5, 1, 8, 5, 3, 7, 5, 3, 10, 6, 3, 6, 6, 5, 6, 5, 6, 5, 5, 4, 8, 3, 9, 5, 5, 7, 2, 11, 3, 10, 3, 10, 6, 6, 9, 5, 8, 6, 5, 8, 5, 10, 6, 12, 6, 10, 6, 5, 10, 4, 6, 8, 5, 13
Offset: 1

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Author

Antti Karttunen, Apr 06 2022

Keywords

Comments

Restricted growth sequence transform of A278222(A109812(n)), or equally of, A278222(A351965(n)).
For all i, j: A351578(i) = A351578(j) => a(i) = a(j) => A352884(i) = A352884(j).

Crossrefs

Programs

  • PARI
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    v109812 = readvec("b109812_to10e5.txt"); \\ Prepared from b-file data with gawk ' { print $2 } '
    up_to = #v109812;
    A109812(n) = v109812[n];
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    v351963 = rgs_transform(vector(up_to, n, A046523(A005940(1+A109812(n)))));
    A351963(n) = v351963[n];

A351965 The odd part of A109812(n).

Original entry on oeis.org

1, 1, 1, 3, 1, 5, 5, 1, 3, 9, 9, 3, 17, 7, 1, 7, 3, 33, 5, 11, 9, 19, 5, 21, 17, 13, 3, 15, 1, 11, 41, 33, 25, 19, 65, 13, 37, 9, 23, 3, 27, 17, 35, 7, 67, 11, 5, 39, 11, 1, 29, 49, 129, 15, 97, 65, 45, 41, 33, 21, 69, 25, 73, 13, 37, 49, 35, 7, 71, 17, 51, 19, 131, 15, 3, 31, 5, 75, 9, 43, 21, 137, 27, 193, 23, 81
Offset: 1

Views

Author

Antti Karttunen, Apr 06 2022

Keywords

Crossrefs

Cf. A000265, A109812, A351963, A351964, A352884 (binary weight).

Programs

  • PARI
    v109812 = readvec("b109812_to10e5.txt"); \\ Prepared from b-file data with gawk ' { print $2 } '
    up_to = #v109812;
    A109812(n) = v109812[n];
    A000265(n) = (n>>valuation(n,2));
    A351965(n) = A000265(A109812(n));

Formula

a(n) = A000265(A109812(n)).
a(n) = A109812(n) / (2^A351964(n)).

A352889 Number of runs in the binary expansion of A109812(n).

Original entry on oeis.org

1, 2, 2, 1, 2, 3, 4, 2, 2, 3, 4, 2, 3, 2, 2, 1, 2, 3, 4, 3, 4, 3, 4, 5, 4, 3, 2, 1, 2, 4, 5, 4, 3, 4, 3, 4, 5, 4, 3, 2, 3, 4, 3, 2, 3, 4, 4, 3, 4, 2, 3, 4, 3, 2, 3, 4, 5, 6, 4, 6, 5, 4, 5, 4, 6, 3, 4, 2, 3, 4, 3, 4, 3, 2, 2, 1, 4, 5, 4, 5, 6, 5, 4, 3, 4, 5, 4, 3, 4, 5, 6, 7, 6, 5, 6, 4, 5, 2, 5, 4, 4, 3, 2, 3, 4
Offset: 1

Views

Author

Antti Karttunen, Apr 07 2022

Keywords

Examples

			   n   A109812(n)  [in base-2]   a(n) = number of runs
-----+-------------------------------------------------
   1 |          1       [1],      1
   2 |          2      [10],      2
   3 |          4     [100],      2
   4 |          3      [11],      1
   5 |          8    [1000],      2
   6 |          5     [101],      3
   7 |         10    [1010],      4
   8 |         16   [10000],      2
   9 |          6     [110],      2
  10 |          9    [1001],      3
  11 |         18   [10010],      4
		

Crossrefs

Programs

  • PARI
    v109812 = readvec("b109812_to10e5.txt"); \\ Prepared from b-file data with gawk ' { print $2 } '
    up_to = #v109812;
    A109812(n) = v109812[n];
    A352889(n) = A005811(A109812(n));

Formula

a(n) = A005811(A109812(n)).

A352791 a(n) is the number of numbers k < n such that A109812(k) AND A109812(n) = 0 (where AND denotes the bitwise AND operator).

Original entry on oeis.org

0, 1, 2, 1, 4, 2, 3, 7, 3, 4, 5, 5, 6, 3, 14, 3, 8, 10, 8, 4, 11, 5, 12, 5, 11, 5, 14, 3, 28, 7, 8, 18, 8, 8, 18, 8, 9, 21, 5, 26, 5, 21, 9, 11, 11, 11, 25, 6, 15, 49, 7, 16, 29, 8, 16, 31, 8, 17, 33, 14, 14, 15, 16, 16, 16, 15, 15, 18, 8, 40, 9, 18, 21, 11
Offset: 1

Views

Author

Rémy Sigrist, Apr 03 2022

Keywords

Comments

The magnitude of a(n) is related to A352884(n), the Hamming weight of A109812(n) (see illustration in Links section).

Examples

			The first terms, alongside the binary expansion of A109812(n) and the corresponding k's, are:
  n   a(n)  bin(b(n))  k's
  --  ----  ---------  -----------------------------------------------
   1     0          1  []
   2     1         10  [1]
   3     2        100  [1, 2]
   4     1         11  [3]
   5     4       1000  [1, 2, 3, 4]
   6     2        101  [2, 5]
   7     3       1010  [1, 3, 6]
   8     7      10000  [1, 2, 3, 4, 5, 6, 7]
   9     3        110  [1, 5, 8]
  10     4       1001  [2, 3, 8, 9]
  11     5      10010  [1, 3, 5, 6, 10]
  12     5       1100  [1, 2, 4, 8, 11]
  13     6      10001  [2, 3, 5, 7, 9, 12]
  14     3       1110  [1, 8, 13]
  15    14     100000  [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]
  16     3        111  [5, 8, 15]
		

Crossrefs

Formula

a(n) <= n-1 with equality iff A109812(n) is a power of 2.
Showing 1-5 of 5 results.