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.

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A268670 a(n) = A006068(A268669(n)).

Original entry on oeis.org

1, 3, 1, 7, 1, 3, 5, 15, 5, 3, 13, 7, 9, 11, 1, 31, 1, 11, 29, 7, 25, 27, 9, 15, 17, 19, 5, 23, 13, 3, 21, 63, 21, 3, 61, 23, 57, 59, 13, 15, 49, 51, 17, 55, 5, 19, 53, 31, 33, 35, 1, 39, 29, 11, 37, 47, 9, 27, 45, 7, 41, 43, 25, 127, 25, 43, 125, 7, 121, 123, 41, 47, 113, 115, 9, 119, 45, 27, 117, 31, 97, 99, 33, 103, 1
Offset: 1

Views

Author

Antti Karttunen, Feb 10 2016

Keywords

Comments

All terms are odd, by definition.

Crossrefs

Cf. A001317 (positions of ones).

Programs

Formula

a(n) = A006068(A268669(n)).

A268716 a(n) = 2*A006068(n); main diagonal of A268714.

Original entry on oeis.org

0, 2, 6, 4, 14, 12, 8, 10, 30, 28, 24, 26, 16, 18, 22, 20, 62, 60, 56, 58, 48, 50, 54, 52, 32, 34, 38, 36, 46, 44, 40, 42, 126, 124, 120, 122, 112, 114, 118, 116, 96, 98, 102, 100, 110, 108, 104, 106, 64, 66, 70, 68, 78, 76, 72, 74, 94, 92, 88, 90, 80, 82, 86, 84, 254, 252, 248, 250, 240, 242, 246, 244, 224, 226
Offset: 0

Views

Author

Antti Karttunen, Feb 12 2016

Keywords

Crossrefs

Main diagonal of array A268714.
Row 3 and column 3 of array A268724.

Programs

Formula

a(n) = 2*A006068(n).
a(n) = A006068(A001969(n+1)).
a(n) = A268714(n,n).

A277902 If A010060(n) = 1, a(n) = A000069(A268671(n)), otherwise a(n) = A001969(1+a(A006068(n)/2)).

Original entry on oeis.org

1, 2, 3, 7, 6, 5, 4, 14, 9, 10, 13, 15, 8, 11, 12, 31, 24, 23, 28, 30, 25, 26, 17, 29, 16, 19, 18, 22, 27, 20, 21, 62, 43, 40, 61, 45, 56, 59, 54, 58, 49, 50, 33, 55, 36, 39, 52, 63, 32, 35, 48, 38, 57, 46, 37, 47, 34, 53, 44, 60, 41, 42, 51, 127, 102, 85, 124, 120, 121, 122, 83, 95, 112, 115, 68, 118, 89, 106
Offset: 1

Views

Author

Antti Karttunen, Nov 03 2016

Keywords

Comments

a(n) gives the number that is in the same position in array A277880 as where n is located in array A277820.

Examples

			The top left corner of array A277820 is:
   1,  3,  5, 15
   2,  6, 10, 30
   7,  9, 27, 45
   4, 12, 20, 60
  13, 23, 57, 75
while the top left corner of A277880 is:
   1,  3,  6, 12
   2,  5, 10, 20
   4,  9, 18, 36
   7, 15, 30, 60
   8, 17, 34, 68
thus for example, a(1) = 1, a(2) = 2, a(3) = 3, a(4) = 7, a(5) = 6, a(6) = 5, a(7) = 4, a(9) = 9, a(12) = 15, a(13) = 8 and a(27) = 18.
		

Crossrefs

Inverse: A277901.
Related permutations and arrays: A277820, A277821, A277880.

Formula

If A010060(n) = 1 [when n is one of the odious numbers, A000069], then a(n) = A000069(A268671(n)), otherwise a(n) = A001969(1+a(A006068(n)/2)).
As a composition of other permutations:
a(n) = A277880(A277821(n)).
Other identities. For all n >= 1:
A010060(a(n)) = A010060(n). [Preserves the parity of binary weight.]
a(A001317(n)) = A003945(n).
a(A065621(n)) = A000069(n).
a(A277823(n)) = A129771(n).
a(A277825(n)) = 2*A129771(n).

A297110 Xor-Moebius transform of A006068, inverse of the binary Gray code.

Original entry on oeis.org

1, 2, 3, 4, 7, 4, 4, 8, 12, 8, 12, 8, 8, 12, 15, 16, 31, 20, 28, 16, 31, 20, 27, 16, 23, 24, 28, 24, 23, 16, 20, 32, 48, 32, 63, 40, 56, 36, 48, 32, 48, 32, 51, 40, 48, 44, 52, 32, 36, 56, 63, 48, 39, 36, 47, 48, 48, 56, 44, 32, 40, 60, 63, 64, 112, 80, 124, 64, 96, 64, 123, 80, 112, 72, 111, 72, 127, 80, 116, 64
Offset: 1

Views

Author

Antti Karttunen, Dec 25 2017

Keywords

Comments

Unique sequence satisfying SumXOR_{d divides n} a(d) = A006068(n) for all n > 0, where SumXOR is the analog of summation under the binary XOR operation. See A295901 for a list of some of the properties of the Xor-Moebius transform.

Crossrefs

Programs

  • PARI
    A006068(n)= { my(s=1, ns); while(1, ns = n >> s; if(0==ns, break()); n = bitxor(n, ns); s <<= 1; ); return (n); } \\ Essentially Joerg Arndt's Jul 19 2012 code.
    A297110(n) = { my(v=0); fordiv(n, d, if(issquarefree(n/d), v=bitxor(v, A006068(d)))); (v); };

A324337 a(n) = A002487(A006068(n)).

Original entry on oeis.org

0, 1, 2, 1, 3, 2, 1, 3, 4, 3, 2, 5, 1, 4, 5, 3, 5, 4, 3, 7, 2, 7, 8, 5, 1, 5, 7, 4, 7, 5, 3, 8, 6, 5, 4, 9, 3, 10, 11, 7, 2, 9, 12, 7, 11, 8, 5, 13, 1, 6, 9, 5, 10, 7, 4, 11, 9, 7, 5, 12, 3, 11, 13, 8, 7, 6, 5, 11, 4, 13, 14, 9, 3, 13, 17, 10, 15, 11, 7, 18, 2, 11, 16, 9, 17, 12, 7, 19, 14, 11, 8, 19, 5, 18, 21, 13, 1, 7, 11, 6, 13, 9, 5, 14, 13, 10
Offset: 0

Views

Author

Antti Karttunen, Feb 23 2019

Keywords

Comments

Like in A324338, a few terms preceding each position n = 2^k seem to be a batch of nearby Fibonacci numbers in some order.
For all n > 0 A324338(n)/A324337(n) constitutes an enumeration system of all positive rationals. For all n > 0 A324338(n) + A324337(n) = A071585(n). - Yosu Yurramendi, Oct 22 2019

Crossrefs

Programs

Formula

From Yosu Yurramendi, Oct 22 2019: (Start)
a(2^m+ k) = A324338(2^m+2^(m-1)+k), m > 0, 0 <= k < 2^(m-1)
a(2^m+2^(m-1)+k) = A324338(2^m+ k), m > 0, 0 <= k < 2^(m-1). (End)
a(n) = A324338(A063946(n)), n > 0. Yosu Yurramendi, Nov 04 2019
a(n) = A002487(A248663(A283477(n))). - Antti Karttunen, Nov 06 2019
a(n) = A002487(1+A233279(n)). - Yosu Yurramendi, Nov 08 2019
From Yosu Yurramendi, Nov 28 2019: (Start)
a(2^(m+1)+k) - a(2^m+k) = A324338(k), m >= 0, 0 <= k < 2^m.
a(A059893(2^(m+1)+A001969(k+1))) - a(A059893(2^m+A001969(k+1))) = A071585(k), m >= 0, 0 <= k < 2^(m-1).
a(A059893(2^(m+1)+ A000069(k+1))) = A071585(k), m >= 1, 0 <= k < 2^(m-1). (End)
From Yosu Yurramendi, Nov 29 2019: (Start)
For n > 0:
A324338(n) + A324337(n) = A071585(n).
A324338(2*A001969(n) )-A324337(2*A001969(n) ) = A071585(n-1)
A324338(2*A001969(n)+1)-A324337(2*A001969(n)+1) = -A324337(n-1)
A324338(2*A000069(n) )-A324337(2*A000069(n) ) = -A071585(n-1)
A324338(2*A000069(n)+1)-A324337(2*A000069(n)+1) = A324338(n-1) (End)
a(n) = A002487(1+A233279(n)). - Yosu Yurramendi, Dec 27 2019

A324338 a(n) = A002487(1+A006068(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 3, 2, 1, 4, 5, 3, 4, 3, 2, 5, 1, 5, 7, 4, 7, 5, 3, 8, 5, 4, 3, 7, 2, 7, 8, 5, 1, 6, 9, 5, 10, 7, 4, 11, 9, 7, 5, 12, 3, 11, 13, 8, 6, 5, 4, 9, 3, 10, 11, 7, 2, 9, 12, 7, 11, 8, 5, 13, 1, 7, 11, 6, 13, 9, 5, 14, 13, 10, 7, 17, 4, 15, 18, 11, 11, 9, 7, 16, 5, 17, 19, 12, 3, 14, 19, 11, 18, 13, 8, 21, 7, 6, 5, 11, 4, 13, 14, 9, 3, 13
Offset: 0

Views

Author

Antti Karttunen, Feb 23 2019

Keywords

Comments

Like in A324337, a few terms preceding each 2^k-th term (here always 1) seem to consist of a batch of nearby Fibonacci numbers (A000045) in some order. For example, a(65533) = 987, a(65534) = 610 and a(65535) = 1597.
For all n > 0 A324338(n)/A324337(n) constitutes an enumeration system of all positive rationals. For all n > 0 A324338(n) + A324337(n) = A071585(n). - Yosu Yurramendi, Oct 22 2019

Crossrefs

Programs

Formula

a(n) = A002487(1+A006068(n)).
a(2^n) = 1 for all n >= 0.
From Yosu Yurramendi, Oct 22 2019: (Start)
a(2^m+2^(m-1)+k) = A324337(2^m+ k), m > 0, 0 <= k < 2^(m-1)
a(2^m+ k) = A324337(2^m+2^(m-1)+k), m > 0, 0 <= k < 2^(m-1). (End)
a(n) = A324337(A063946(n)), n > 0. Yosu Yurramendi, Nov 04 2019
a(n) = A002487(A233279(n)), n > 0. Yosu Yurramendi, Nov 08 2019
From Yosu Yurramendi, Nov 28 2019: (Start)
a(2^(m+1)+k) - a(2^m+k) = A324337(k), m >= 0, 0 <= k < 2^m.
a(A059893(2^(m+1)+A000069(k+1))) - a(A059893(2^m+A000069(k+1))) = A071585(k), m >= 1, 0 <= k < 2^(m-1).
a(A059893(2^m+ A001969(k+1))) = A071585(k), m >= 0, 0 <= k < 2^(m-1). (End)
From Yosu Yurramendi, Nov 29 2019: (Start)
For n > 0:
A324338(n) + A324337(n) = A071585(n).
A324338(2*A001969(n) )-A324337(2*A001969(n) ) = A071585(n-1)
A324338(2*A001969(n)+1)-A324337(2*A001969(n)+1) = -A324337(n-1)
A324338(2*A000069(n) )-A324337(2*A000069(n) ) = -A071585(n-1)
A324338(2*A000069(n)+1)-A324337(2*A000069(n)+1) = A324338(n-1) (End)
a(n) = A002487(A233279(n)). Yosu Yurramendi, Dec 27 2019

A339695 Let G be the undirected graph with nodes {g_k, k >= 0} such that for any k >= 0, g_k is connected to g_{k+1} and g_{A006068(k)} is connected to g_{A006068(k+1)}; a(n) is the distance between g_0 and g_n.

Original entry on oeis.org

0, 1, 2, 2, 3, 4, 4, 3, 4, 5, 6, 6, 6, 5, 6, 5, 6, 7, 8, 8, 9, 10, 10, 9, 9, 8, 7, 8, 9, 9, 8, 7, 8, 9, 10, 10, 11, 12, 12, 11, 12, 13, 14, 14, 14, 13, 14, 13, 13, 12, 12, 11, 10, 9, 10, 11, 12, 13, 14, 14, 13, 13, 12, 11, 12, 13, 14, 14, 15, 16, 16, 15, 16
Offset: 0

Views

Author

Rémy Sigrist, Dec 13 2020

Keywords

Crossrefs

See A339731 for a similar sequence.

Programs

  • PARI
    See Links section.

Formula

abs(a(n) - a(k)) <= abs(n-k) for any n, k >= 0.
a(n) = A339697(n, 0).

A268719 Triangular table T(n>=0,k=0..n) = A003188(A006068(n) + A006068(k)), read by rows as A(0,0), A(1,0), A(1,1), A(2,0), A(2,1), A(2,2), ...

Original entry on oeis.org

0, 1, 3, 2, 6, 5, 3, 2, 7, 6, 4, 12, 15, 13, 9, 5, 4, 13, 12, 11, 10, 6, 7, 4, 5, 14, 15, 12, 7, 5, 12, 4, 10, 14, 13, 15, 8, 24, 27, 25, 29, 31, 26, 30, 17, 9, 8, 25, 24, 31, 30, 27, 26, 19, 18, 10, 11, 8, 9, 26, 27, 24, 25, 22, 23, 20, 11, 9, 24, 8, 30, 26, 25, 27, 18, 22, 21, 23, 12, 13, 14, 15, 8, 9, 10, 11, 28, 29, 30, 31, 24
Offset: 0

Views

Author

Antti Karttunen, Feb 13 2016

Keywords

Examples

			The first fifteen rows of the triangle:
                             0
                           1   3
                         2   6   5
                       3   2   7   6
                     4  12  15  13   9
                   5   4  13  12  11  10
                 6   7   4   5  14  15  12
               7   5  12   4  10  14  13  15
             8  24  27  25  29  31  26  30  17
           9   8  25  24  31  30  27  26  19  18
        10  11   8   9  26  27  24  25  22  23  20
      11   9  24   8  30  26  25  27  18  22  21  23
    12  13  14  15   8   9  10  11  28  29  30  31  24
  13  15  10  14  24   8  11   9  20  28  31  29  25  27
14  10   9  11  27  25   8  24  23  21  28  20  26  30  29
		

Crossrefs

Cf. A001477 (left edge), A001969 (right edge).
Cf. A268720 (row sums).

Programs

  • Mathematica
    a88[n_] := BitXor[n, Floor[n/2]];
    a68[n_] := BitXor @@ Table[Floor[n/2^m], {m, 0, Floor[Log[2, n]]}];
    a68[0] = 0;
    T[n_, k_] := a88[a68[n] + a68[k]];
    Table[T[n, k], {n, 0, 12}, {k, 0, n}] // Flatten (* Jean-François Alcover, Nov 19 2019 *)
  • Python
    def a003188(n): return n^(n>>1)
    def a006068(n):
        s=1
        while True:
            ns=n>>s
            if ns==0: break
            n=n^ns
            s<<=1
        return n
    def T(n, k): return a003188(a006068(n) + a006068(k))
    for n in range(21): print([T(n, k) for k in range(n + 1)]) # Indranil Ghosh, Jun 07 2017
  • Scheme
    (define (A268719 n) (A268715bi (A003056 n) (A002262 n)))
    

Formula

T(n,k) = A003188(A006068(n) + A006068(k)).
a(n) = A268715(A003056(n), A002262(n)). [As a linear sequence.]

A268720 Row sums of A268719: a(n) = Sum_{k=0..n} A003188(A006068(n)+A006068(k)).

Original entry on oeis.org

0, 4, 13, 18, 53, 55, 63, 80, 217, 217, 205, 244, 234, 264, 305, 328, 881, 877, 841, 916, 790, 864, 977, 988, 900, 956, 1021, 1070, 1197, 1235, 1267, 1344, 3553, 3541, 3457, 3604, 3310, 3456, 3681, 3684, 3100, 3244, 3453, 3478, 3917, 3931, 3883, 4048, 3528, 3636, 3757, 3850, 4021, 4111, 4199, 4320, 4745, 4817
Offset: 0

Views

Author

Antti Karttunen, Feb 13 2016

Keywords

Crossrefs

Row sums of triangle A268719.

Programs

  • Scheme
    (define (A268720 n) (add (lambda (k) (A268715bi n k)) 0 n)) ;; Code for A268715bi given in A268715.
    (define (add intfun lowlim uplim) (let sumloop ((i lowlim) (res 0)) (cond ((> i uplim) res) (else (sumloop (1+ i) (+ res (intfun i)))))))

Formula

a(n) = Sum_{k=0..n} A003188(A006068(n)+A006068(k)).

A268721 Convolution of A006068 (inverse of Gray code) with itself: a(n) = Sum_{k=1..n+1} A006068(k) * A006068(1+n-k).

Original entry on oeis.org

0, 1, 6, 13, 26, 58, 72, 107, 160, 230, 286, 440, 558, 599, 696, 851, 1032, 1298, 1510, 1826, 2122, 2353, 2624, 3294, 3884, 4335, 4870, 5001, 5242, 5722, 6048, 6699, 7424, 8226, 8990, 10166, 11226, 12069, 13048, 14384, 15664, 16885, 18134, 19071, 20094, 21276, 22360, 25150, 27788, 30091, 32582, 34343, 36262
Offset: 0

Views

Author

Antti Karttunen, Feb 13 2016

Keywords

Crossrefs

Antidiagonal sums of array A268724.

Programs

  • Scheme
    (define A268721 (CONVOLVE 1 A006068 A006068)) ;; This version requires Antti Karttunen's IntSeq-library.
    ;; More stand-alone version:
    (define (A268721 n) (add (lambda (k) (* (A006068 k) (A006068 (- (+ n 1) k)))) 1 (+ n 1)))
    (define (add intfun lowlim uplim) (let sumloop ((i lowlim) (res 0)) (cond ((> i uplim) res) (else (sumloop (1+ i) (+ res (intfun i)))))))

Formula

a(n) = Sum_{k=1..n+1} A006068(k) * A006068(1+n-k).
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