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 1-10 of 11 results. Next

A250252 Inverse permutation to A114881.

Original entry on oeis.org

1, 2, 3, 4, 6, 7, 10, 5, 15, 11, 21, 16, 28, 9, 36, 22, 45, 29, 55, 14, 66, 37, 78, 8, 91, 20, 105, 46, 120, 56, 136, 27, 153, 13, 171, 67, 190, 35, 210, 79, 231, 92, 253, 44, 276, 106, 300, 12, 325, 54, 351, 121, 378, 19, 406, 65, 435, 137, 465, 154, 496, 77, 528, 26, 561, 172, 595, 90, 630, 191, 666, 211, 703, 104, 741, 18
Offset: 1

Views

Author

Antti Karttunen, Nov 15 2014

Keywords

Crossrefs

Inverse: A114881.
Similar or related permutations: A209268, A249812.
Differs from A246274 for the first time at n=20, where a(20) = 14, while
A246274(20) = 20.

Programs

  • Scheme
    (define (A250252 n) (let ((x (A078898 (+ 1 n))) (y (A055396 (+ 1 n)))) (* (/ 1 2) (- (expt (+ x y) 2) x y y y -2))))

Formula

a(n) = 1 + ((((x+y)^2) - x - 3*y)/2), where x = A078898(n+1) and y = A055396(n+1).
As a composition of related permutations:
a(n) = A209268(A249812(n)).
Other identities. For all n >= 1 the following holds:
a(A005408(n-1)) = A000217(n). [Maps odd numbers to triangular numbers.]
a(A006093(n)) = A000124(n-1). [Maps precedents of primes to central polygonal numbers.]

A114882 Transposition sequence of A114881.

Original entry on oeis.org

1, 3, 2, 5, 4, 7, 6, 8, 10, 9, 12, 11, 16, 24, 18, 13, 22, 15, 28, 48, 30, 17, 36, 14, 40, 120
Offset: 1

Views

Author

Clark Kimberling, Jan 03 2006

Keywords

Comments

A self-inverse permutation of the natural numbers.

Examples

			Start with the northwest corner of A114881:
1 3 5 7 9
2 8 14 20 26
4 24 34 54 64
6 48 76 90 118
a(1)=1 because 1=T(1,1) and T(1,1)=1.
a(2)=3 because 2=T(2,1) and T(1,2)=3.
a(3)=2 because 3=T(1,2) and T(2,1)=2.
a(20)=48 because 20=T(2,4) and T(4,2)=48.
		

Crossrefs

Formula

(See A114538 for definition of transposition sequence.)

A249743 Main diagonal of square arrays A114881 and A249741.

Original entry on oeis.org

1, 8, 34, 90, 208, 376, 628, 816, 1218, 1768, 2200, 2922, 3648, 4342, 5028, 5988, 7728, 8478, 10116, 11572, 12628, 14298, 16018, 17710, 21630, 23128, 24616, 26856, 28666, 30622, 35686, 38382, 42606, 44062, 50212, 52698, 56362, 60798, 63960, 68680, 73210, 76200, 82702, 85498, 90028, 92136, 101068, 109492, 114180, 119308, 126052, 133122
Offset: 1

Views

Author

Antti Karttunen, Nov 15 2014

Keywords

Comments

One less than the main diagonal of square arrays A083140 and A083221 formed from the sieve of Eratosthenes.

Crossrefs

One less than A083141.

Programs

Formula

a(1) = 1, a(n) = (A000040(n) * A000040(2*(n-1))) - 1. [Where A000040(n) gives the n-th prime, p_n].
a(n) = A083140(n,n) - 1 = A083221(n,n) - 1.
a(n) = A083141(n+1)-1. [With the current starting offset 2 of A083141].

A249741 Sieve of Eratosthenes minus one: a(n) = A083221(n+1) - 1.

Original entry on oeis.org

1, 3, 2, 5, 8, 4, 7, 14, 24, 6, 9, 20, 34, 48, 10, 11, 26, 54, 76, 120, 12, 13, 32, 64, 90, 142, 168, 16, 15, 38, 84, 118, 186, 220, 288, 18, 17, 44, 94, 132, 208, 246, 322, 360, 22, 19, 50, 114, 160, 252, 298, 390, 436, 528, 28, 21, 56, 124, 202, 318, 376, 492, 550, 666, 840, 30, 23, 62, 144, 216, 340, 402, 526, 588, 712, 898, 960, 36, 25
Offset: 1

Views

Author

Antti Karttunen, Nov 15 2014

Keywords

Examples

			The top left corner of the array:
   1,   3,   5,    7,    9,   11,   13,   15,   17,   19,   21,   23,   25,
   2,   8,  14,   20,   26,   32,   38,   44,   50,   56,   62,   68,   74,
   4,  24,  34,   54,   64,   84,   94,  114,  124,  144,  154,  174,  184,
   6,  48,  76,   90,  118,  132,  160,  202,  216,  258,  286,  300,  328,
  10, 120, 142,  186,  208,  252,  318,  340,  406,  450,  472,  516,  582,
  12, 168, 220,  246,  298,  376,  402,  480,  532,  558,  610,  688,  766,
  16, 288, 322,  390,  492,  526,  628,  696,  730,  798,  900, 1002, 1036,
  18, 360, 436,  550,  588,  702,  778,  816,  892, 1006, 1120, 1158, 1272,
  22, 528, 666,  712,  850,  942,  988, 1080, 1218, 1356, 1402, 1540, 1632,
  28, 840, 898, 1072, 1188, 1246, 1362, 1536, 1710, 1768, 1942, 2058, 2116,
...
		

Crossrefs

Inverse: A249742.
Transpose: A114881.
Row 1: A005408, Column 1: A006093, Main diagonal: A249743.

Programs

Formula

a(n) = A083221(n+1) - 1.
As a composition of related permutations:
a(n) = A114881(A038722(n)).
a(n) = A249811(A135764(n)).

A249811 Permutation of natural numbers: a(n) = A249741(A001511(n), A003602(n)).

Original entry on oeis.org

1, 2, 3, 4, 5, 8, 7, 6, 9, 14, 11, 24, 13, 20, 15, 10, 17, 26, 19, 34, 21, 32, 23, 48, 25, 38, 27, 54, 29, 44, 31, 12, 33, 50, 35, 64, 37, 56, 39, 76, 41, 62, 43, 84, 45, 68, 47, 120, 49, 74, 51, 94, 53, 80, 55, 90, 57, 86, 59, 114, 61, 92, 63, 16, 65, 98, 67, 124, 69, 104, 71, 118, 73, 110, 75, 144, 77, 116, 79, 142, 81
Offset: 1

Views

Author

Antti Karttunen, Nov 06 2014

Keywords

Comments

In the essence, a(n) tells which number in square array A249741 (the sieve of Eratosthenes minus 1) is at the same position where n is in array A135764, which is formed from odd numbers whose binary expansions are shifted successively leftwards on the successive rows. As the topmost row in both arrays is A005408 (odd numbers), they are fixed, i.e., a(2n+1) = 2n+1 for all n.
Equally: a(n) tells which number in array A114881 is at the same position where n is in the array A054582, as they are the transposes of above two arrays.

Crossrefs

Inverse: A249812.
Similar or related permutations: A249814 ("deep variant"), A246676, A249815, A114881, A209268, A249725, A249741.
Differs from A246676 for the first time at n=14, where a(14)=20, while
A246676(14)=26.

Programs

Formula

In the following formulas, A083221 and A249741 are interpreted as bivariate functions:
a(n) = A083221(A001511(n),A003602(n)) - 1 = A249741(A001511(n),A003602(n)).
As a composition of related permutations:
a(n) = A114881(A209268(n)).
a(n) = A249741(A249725(n)).
a(n) = A249815(A246676(n)).
Other identities. For all n >= 1 the following holds:
a(A000079(n-1)) = A006093(n).

A249815 Permutation of natural numbers: a(n) = A249741(A055396(n+1), A246277(n+1)).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 26, 21, 22, 23, 24, 25, 20, 27, 28, 29, 30, 31, 38, 33, 34, 35, 36, 37, 62, 39, 40, 41, 42, 43, 32, 45, 46, 47, 48, 49, 74, 51, 52, 53, 64, 55, 98, 57, 58, 59, 60, 61, 56, 63, 94, 65, 66, 67, 110, 69, 70, 71, 72, 73, 50, 75, 76, 77, 78, 79, 44, 81, 82, 83
Offset: 1

Views

Author

Antti Karttunen, Nov 06 2014

Keywords

Comments

a(n) tells which number in square array A249741 (the sieve of Eratosthenes minus 1) is at the same position where n is in array A246275. As the topmost row in both arrays is A005408 (odd numbers), they are fixed, i.e. a(2n+1) = 2n+1 for all n. Also, as the leftmost column in both arrays is primes minus one (A006093), they are also among the fixed points.
Equally: a(n) tells which number in array A114881 is at the same position where n is in the array A246273, as they are the transposes of above two arrays.

Crossrefs

Inverse: A249816
Similar or related permutations: A250244 ("deep variant"), A246675, A249811, A249817, A246273, A246275, A114881, A249741.
Differs from A249816 and A250243 for the first time at n=32, where a(32) = 38, while A249816(32) = A250243(32) = 44.
Differs from A250244 for the first time at n=39, where a(39) = 39, while A250244(39) = 51.

Programs

Formula

a(n) = A249741(A055396(n+1), A246277(n+1)).
As a composition of other permutations:
a(n) = A249811(A246675(n)).
a(n) = A249817(n+1) - 1.
Other identities. For all n >= 1:
a(A005408(n-1)) = A005408(n-1) and a(A006093(n)) = A006093(n). [Fixes odd numbers and precedents of primes. Cf. comments above].

A250472 Permutation of natural numbers: a(n) = A250470(2*n - 1).

Original entry on oeis.org

1, 2, 3, 5, 4, 7, 11, 6, 13, 17, 8, 19, 9, 10, 23, 29, 12, 15, 31, 14, 37, 41, 16, 43, 25, 18, 47, 21, 20, 53, 59, 22, 27, 61, 24, 67, 71, 26, 35, 73, 28, 79, 33, 30, 83, 55, 32, 39, 89, 34, 97, 101, 36, 103, 107, 38, 109, 45, 40, 65, 49, 42, 51, 113, 44, 127, 85, 46, 131, 137, 48, 77, 57, 50, 139, 149, 52, 63, 151, 54, 95, 157, 56, 163, 121, 58, 167, 69, 60
Offset: 1

Views

Author

Antti Karttunen, Dec 06 2014

Keywords

Comments

For n > 1, a(n) tells which number is located immediately above n in the sieve of Eratosthenes (see A083140, A083221) in the same column of the sieve that contains 2n - 1.

Crossrefs

Inverse: A250471.
Odd bisection of A250470. The other bisection: A250479.

Formula

a(1) = 1, a(n) = A083221(A055396(2*n - 1)-1, A078898(2*n - 1)).
a(n) = A250470(2*n - 1).

A246273 Transpose of square array A246275.

Original entry on oeis.org

1, 2, 3, 4, 8, 5, 6, 24, 14, 7, 10, 48, 34, 26, 9, 12, 120, 76, 124, 20, 11, 16, 168, 142, 342, 54, 44, 13, 18, 288, 220, 1330, 90, 174, 32, 15, 22, 360, 322, 2196, 186, 538, 64, 80, 17, 28, 528, 436, 4912, 246, 1572, 118, 624, 74, 19, 30, 840, 666, 6858, 390, 2872, 208, 2400, 244, 62, 21
Offset: 1

Views

Author

Antti Karttunen, Aug 21 2014

Keywords

Examples

			The top-left corner of the array:
   1,     2,     4,     6,    10,    12,    16,    18,    22,   ...
   3,     8,    24,    48,   120,   168,   288,   360,   528,   ...
   5,    14,    34,    76,   142,   220,   322,   436,   666,   ...
   7,    26,   124,   342,  1330,  2196,  4912,  6858, 12166,   ...
   9,    20,    54,    90,   186,   246,   390,   550,   712,   ...
  11,    44,   174,   538,  1572,  2872,  5490,  8302, 15340,   ...
  ...
		

Crossrefs

Inverse permutation: A246274.
Transpose: A246275.
Other related permutations: A038722, A054582, A246675, A246676.
One less than A246279.
Cf. A114881.

Programs

Formula

a(n) = A246279(n) - 1.
As a composition of related permutations:
a(n) = A246275(A038722(n)).
a(n) = A246676(A054582(n-1)).

A249812 Permutation of natural numbers: a(n) = A000079(A055396(n+1)-1) * ((2*A078898(n+1))-1).

Original entry on oeis.org

1, 2, 3, 4, 5, 8, 7, 6, 9, 16, 11, 32, 13, 10, 15, 64, 17, 128, 19, 14, 21, 256, 23, 12, 25, 18, 27, 512, 29, 1024, 31, 22, 33, 20, 35, 2048, 37, 26, 39, 4096, 41, 8192, 43, 30, 45, 16384, 47, 24, 49, 34, 51, 32768, 53, 28, 55, 38, 57, 65536, 59, 131072, 61, 42, 63, 36, 65, 262144, 67, 46, 69, 524288, 71, 1048576, 73, 50, 75, 40, 77, 2097152, 79, 54, 81, 4194304, 83, 44
Offset: 1

Views

Author

Antti Karttunen, Nov 06 2014

Keywords

Comments

In the essence, a(n) tells which number in the array A135764 is at the same position where n is in the array A249741, the sieve of Eratosthenes minus 1. As the topmost row in both arrays is A005408 (odd numbers), they are fixed, i.e., a(2n+1) = 2n+1 for all n.
Equally: a(n) tells which number in array A054582 is at the same position where n is in the array A114881, as they are the transposes of above two arrays.

Crossrefs

Inverse: A249811.
Similar or related permutations: A249813 ("deep variant"), A246675, A249816, A054582, A114881, A250252, A135764, A249741, A249742.
Differs from A246675 for the first time at n=20, where a(20)=14, while A246675(20)=18.

Programs

Formula

a(n) = A000079(A055396(n+1)-1) * ((2*A078898(n+1))-1).
As a composition of related permutations:
a(n) = A054582(A250252(n)-1).
a(n) = A135764(A249742(n)).
a(n) = A246675(A249816(n)).
Other identities. For all n >= 1 the following holds:
a(A006093(n)) = A000079(n-1).

A249816 Permutation of natural numbers: a(n) = A246275(A055396(n+1), A078898(n+1)).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 26, 21, 22, 23, 24, 25, 20, 27, 28, 29, 30, 31, 44, 33, 34, 35, 36, 37, 32, 39, 40, 41, 42, 43, 80, 45, 46, 47, 48, 49, 74, 51, 52, 53, 124, 55, 62, 57, 58, 59, 60, 61, 38, 63, 54, 65, 66, 67, 134, 69, 70, 71, 72, 73, 50, 75, 76, 77, 78, 79, 98, 81, 82, 83
Offset: 1

Views

Author

Antti Karttunen, Nov 06 2014

Keywords

Comments

a(n) tells which number in square array A246275 is at the same position where n is in array A249741, the sieve of Eratosthenes minus 1. As the topmost row in both arrays is A005408 (odd numbers), they are fixed, i.e. a(2n+1) = 2n+1 for all n. Also, as the leftmost column in both arrays is primes minus one (A006093), they are also among the fixed points.
Equally: a(n) tells which number in array A246273 is at the same position where n is in the array A114881, as they are the transposes of above two arrays.

Crossrefs

Inverse: A249815.
Similar or related permutations: A250243 ("deep variant"), A246676, A249812, A249818, A246273, A246275, A114881, A249741.
Differs from A249815 and A250244 for the first time at n=32, where a(32) = 44, while A249815(32) = A250244(32) = 38.
Differs from A250244 for the first time at n=39, where a(39) = 39, while A250243(39) = 51.

Programs

Formula

a(n) = A246275(A055396(n+1), A078898(n+1)).
As a composition of other permutations:
a(n) = A246676(A249812(n)).
a(n) = A249818(n+1) - 1.
Other identities. For all n >= 1:
a(A005408(n-1)) = A005408(n-1) and a(A006093(n)) = A006093(n). [Fixes odd numbers and precedents of primes. Cf. comments above].
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