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.

A265345 Square array A(row,col): For row=0, A(0,col) = A265341(col), for row > 0, A(row,col) = A265342(A(row-1,col)).

Original entry on oeis.org

1, 3, 2, 7, 6, 4, 5, 10, 12, 8, 9, 22, 20, 24, 16, 21, 18, 28, 40, 48, 64, 13, 30, 36, 56, 80, 192, 32, 19, 26, 60, 72, 112, 160, 96, 184, 25, 14, 52, 120, 144, 224, 640, 552, 352, 11, 46, 76, 208, 240, 576, 448, 320, 1056, 704, 15, 58, 68, 136, 104, 480, 288, 1720, 1600, 2112, 1408
Offset: 1

Views

Author

Antti Karttunen, Dec 18 2015

Keywords

Comments

Square array A(row,col) is read by downwards antidiagonals as: A(0,0), A(0,1), A(1,0), A(0,2), A(1,1), A(2,0), A(0,3), A(1,2), A(2,1), A(3,0), ...
All the terms in the same column are either all divisible by 3, or none of them are.
Reducing A265342 to its constituent sequences gives A265342(n) = A263273(2*A263273(n)). Iterating this function k times starting from n reduces to (because A263273 is an involution, so pairs of them are canceled) to A263273((2^k)*A263273(n)).

Examples

			The top left corner of the array:
    1,    3,    7,    5,    9,   21,   13,   19,   25,   11,   15,    39, .
    2,    6,   10,   22,   18,   30,   26,   14,   46,   58,   66,    78, .
    4,   12,   20,   28,   36,   60,   52,   76,   68,   44,   84,   156, .
    8,   24,   40,   56,   72,  120,  208,  136,   88,  232,  168,   624, .
   16,   48,   80,  112,  144,  240,  104,  200,  496,  424,  336,   312, .
   64,  192,  160,  224,  576,  480,  520,  256,  344,  608,  672,  1560, .
   32,   96,  640,  448,  288, 1920, 1144,  512, 1984,  736, 1344,  3432, .
  184,  552,  320, 1720, 1656,  960, 2072, 1024, 1376, 4384, 5160,  6216, .
  352, 1056, 1600,  824, 3168, 4800, 3712, 6040, 5344, 2936, 2472, 11136, .
  ...
		

Crossrefs

Inverse: A265346.
Transpose: A265347.
Leftmost column: A264980.
Topmost row: A265341.
Row index: A265330 (zero-based), A265331 (one-based).
Column index: A265910 (zero-based), A265911 (one-based).
Cf. also A265342.
Related permutations: A263273, A265895.

Programs

Formula

For row=0, A(0,col) = A265341(col), for row>0, A(row,col) = A265342(A(row-1,col)).
A(row, col) = A263273((2^row) * A263273(A265341(col))). [The above reduces to this.]

A265895 Square array: A(row,col) = A263273(A265345(row,col)) = 2^row * A263273(A265341(col)).

Original entry on oeis.org

1, 3, 2, 5, 6, 4, 7, 10, 12, 8, 9, 14, 20, 24, 16, 15, 18, 28, 40, 48, 32, 13, 30, 36, 56, 80, 96, 64, 11, 26, 60, 72, 112, 160, 192, 128, 17, 22, 52, 120, 144, 224, 320, 384, 256, 19, 34, 44, 104, 240, 288, 448, 640, 768, 512, 21, 38, 68, 88, 208, 480, 576, 896, 1280, 1536, 1024, 39, 42, 76, 136, 176, 416, 960, 1152, 1792, 2560, 3072, 2048
Offset: 1

Views

Author

Antti Karttunen, Dec 18 2015

Keywords

Comments

Square array A(row,col) is read by downwards antidiagonals as: A(0,0), A(0,1), A(1,0), A(0,2), A(1,1), A(2,0), A(0,3), A(1,2), A(2,1), A(3,0), ...
Shares with arrays A135764, A253551 and A254053 the property that odd terms are on the top row and when going downward in each column, terms grow by doubling.

Examples

			The top left corner of the array:
    1,   3,    5,    7,    9,   15,   13,   11,   17,   19,   21,   39,
    2,   6,   10,   14,   18,   30,   26,   22,   34,   38,   42,   78,
    4,  12,   20,   28,   36,   60,   52,   44,   68,   76,   84,  156,
    8,  24,   40,   56,   72,  120,  104,   88,  136,  152,  168,  312,
   16,  48,   80,  112,  144,  240,  208,  176,  272,  304,  336,  624,
   32,  96,  160,  224,  288,  480,  416,  352,  544,  608,  672, 1248,
   64, 192,  320,  448,  576,  960,  832,  704, 1088, 1216, 1344, 2496,
  128, 384,  640,  896, 1152, 1920, 1664, 1408, 2176, 2432, 2688, 4992,
  256, 768, 1280, 1792, 2304, 3840, 3328, 2816, 4352, 4864, 5376, 9984,
...
		

Crossrefs

Inverse permutation: A265896.
The top row: 1+(2*A263273(n)).
Differs from A135764 for the first time at n=16, where a(16) = 15, while A135764(16) = 11.

Formula

A(row,col) = A263273(A265345(row,col)).
A(row,col) = 2^row * A263273(A265341(col)).

A270426 Permutation of natural numbers: a(1) = 1, a(2n) = 2*a(n), a(2n+1) = A265341(a(n)).

Original entry on oeis.org

1, 2, 3, 4, 7, 6, 5, 8, 9, 14, 19, 12, 13, 10, 21, 16, 25, 18, 11, 28, 63, 38, 23, 24, 17, 26, 27, 20, 15, 42, 37, 32, 57, 50, 73, 36, 31, 22, 39, 56, 33, 126, 91, 76, 117, 46, 61, 48, 43, 34, 75, 52, 79, 54, 29, 40, 67, 30, 49, 84, 157, 74, 45, 64, 147, 114, 41, 100, 183, 146, 77, 72, 35, 62, 51, 44, 55, 78, 53, 112, 193, 66
Offset: 1

Views

Author

Antti Karttunen, Mar 17 2016

Keywords

Comments

This sequence can be represented as a binary tree. Each left hand child will contain 2n, and each right hand child will contain A265341(n), when the parent node contains n:
1
................../ \..................
2 3
4......../ \........7 6......../ \........5
/ \ / \ / \ / \
/ \ / \ / \ / \
/ \ / \ / \ / \
8 9 14 19 12 13 10 21
16 25 18 11 28 63 38 23 24 17 26 27 20 15 42 37
etc.

Crossrefs

Inverse: A270425.
Cf. A265341.

Formula

a(1) = 1, a(2n) = 2*a(n), a(2n+1) = A265341(a(n)).

A265353 Permutation of nonnegative integers: a(n) = A264985(A263273(n)).

Original entry on oeis.org

0, 1, 3, 2, 4, 10, 6, 9, 12, 5, 7, 19, 8, 13, 31, 24, 28, 37, 15, 11, 33, 18, 27, 30, 21, 36, 39, 14, 16, 46, 23, 25, 73, 69, 55, 64, 17, 22, 58, 26, 40, 94, 78, 85, 112, 51, 34, 100, 72, 82, 91, 75, 109, 118, 42, 32, 96, 20, 35, 105, 60, 99, 102, 45, 29, 87, 54, 81, 84, 57, 90, 93, 48, 38, 114, 63, 108, 111, 66, 117, 120, 41
Offset: 0

Views

Author

Antti Karttunen, Dec 07 2015

Keywords

Comments

Composition of A263273 with the permutation obtained from its odd bisection.

Crossrefs

Inverse: A265354.

Programs

  • Python
    from sympy import factorint
    from sympy.ntheory.factor_ import digits
    from operator import mul
    def a030102(n): return 0 if n==0 else int(''.join(map(str, digits(n, 3)[1:][::-1])), 3)
    def a038502(n):
        f=factorint(n)
        return 1 if n==1 else reduce(mul, [1 if i==3 else i**f[i] for i in f])
    def a038500(n): return n/a038502(n)
    def a263273(n): return 0 if n==0 else a030102(a038502(n))*a038500(n)
    def a264985(n): return (a263273(2*n + 1) - 1)/2
    def a(n): return a264985(a263273(n)) # Indranil Ghosh, May 22 2017
  • Scheme
    (define (A265353 n) (A264985 (A263273 n)))
    

Formula

a(n) = A264985(A263273(n)).

A265342 Permutation of even numbers: a(n) = 2 * A265351(n).

Original entry on oeis.org

0, 2, 4, 6, 8, 22, 12, 10, 16, 18, 20, 58, 24, 26, 76, 66, 64, 70, 36, 14, 40, 30, 28, 34, 48, 46, 52, 54, 56, 166, 60, 62, 184, 174, 172, 178, 72, 74, 220, 78, 80, 238, 228, 226, 232, 198, 68, 202, 192, 190, 196, 210, 208, 214, 108, 38, 112, 42, 44, 130, 120, 118, 124, 90, 32, 94, 84, 82, 88, 102, 100, 106, 144
Offset: 0

Views

Author

Antti Karttunen, Dec 07 2015

Keywords

Comments

Iterating this sequence as 1, a(1), a(a(1)), a(a(a(1))), ... yields A264980.

Crossrefs

Cf. A265351.
Cf. also A265341, A263273, A264980.

Programs

  • Python
    from sympy import factorint
    from sympy.ntheory.factor_ import digits
    from operator import mul
    def a030102(n): return 0 if n==0 else int(''.join(map(str, digits(n, 3)[1:][::-1])), 3)
    def a038502(n):
        f=factorint(n)
        return 1 if n==1 else reduce(mul, [1 if i==3 else i**f[i] for i in f])
    def a038500(n): return n/a038502(n)
    def a263273(n): return 0 if n==0 else a030102(a038502(n))*a038500(n)
    def a263272(n): return a263273(2*n)/2
    def a(n): return 2*a263272(a263273(n)) # Indranil Ghosh, May 25 2017
  • Scheme
    (define (A265342 n) (* 2 (A265351 n)))
    

Formula

a(n) = 2 * A265351(n).
Showing 1-5 of 5 results.