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 1-7 of 7 results.

A052288 First differences of the average of two consecutive primes (A024675).

Original entry on oeis.org

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

Views

Author

Labos Elemer, Feb 08 2000

Keywords

Examples

			a(30) = ((113 + 127)/2) - ((127 + 131)/2) = (131 - 113)/2 = 9;
a(31) = ((127 + 131)/2) - ((137 + 131)/2) = (137 - 127)/2 = 5.
		

Programs

Formula

a(n) = (prime(n+3) - prime(n+1))/2.
a(n) = A115061(n+2) = A162345(n+2). - Nathaniel Johnston, Jun 25 2011

A162343 Array read by rows in which row n lists the numbers that are in the same "y" level in the mountain path of the primes.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 9, 10, 13, 14, 17, 18, 25, 26, 15, 16, 19, 24, 27, 20, 23, 28, 33, 34, 21, 22, 29, 32, 35, 30, 31, 36, 37, 38, 41, 42, 49, 50, 39, 40, 43, 48, 51, 44, 47, 52, 45, 46, 53, 54, 59, 60, 55, 58, 61, 68, 69, 56, 57, 62, 67, 70, 75, 76, 63, 66, 71, 74
Offset: 0

Views

Author

Omar E. Pol, Jul 24 2009

Keywords

Comments

See the illustration "The mountain path of the primes", here.

Examples

			Array begins:
0, 1, 2,. . . . . . . . . . . . . . . . . .
. . . 3,. . . . . . . . . . . . . . . . . .
. . . 4, 5, 6,. . . . . . . . . . . . . . .
. . . . . . 7,. . . . . . . . . . . . . . .
. . . . . . 8,11,12,. . . . . . . . . . . .
. . . . . . 9,10,13,. . . . . . . . . . . .
. . . . . . . . .14,17,18,25,26,. . . . . .
. . . . . . . . .15,16,19,24,27,. . . . . .
. . . . . . . . . . . .20,23,28,33,34,. . .
. . . . . . . . . . . .21,22,29,32,35,. . .
. . . . . . . . . . . . . . ,30,31,36,. . .
. . . . . . . . . . . . . . . . . .37,. . .
		

Crossrefs

A162344 Array read by rows in which row n lists the numbers that are in the same "x" level in the mountain path of the primes.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 10, 12, 13, 14, 15, 17, 16, 18, 19, 20, 21, 25, 24, 23, 22, 26, 27, 28, 29, 30, 33, 32, 31, 34, 35, 36, 37, 38, 39, 41, 40, 42, 43, 44, 45, 49, 48, 47, 46, 50, 51, 52, 53, 54, 55, 56, 59, 58, 57, 60, 61, 62, 63, 64, 68, 67, 66, 65, 69, 70, 71, 72
Offset: 0

Views

Author

Omar E. Pol, Jul 24 2009

Keywords

Comments

See the illustration "The mountain path of the primes", here.

Examples

			Array begins:
0, 1, 2,. . . . . . . . . . . . . . . . . .
. . . 3,. . . . . . . . . . . . . . . . . .
. . . 4, 5, 6,. . . . . . . . . . . . . . .
. . . . . . 7,. . . . . . . . . . . . . . .
. . . . . . 8,11,12,. . . . . . . . . . . .
. . . . . . 9,10,13,. . . . . . . . . . . .
. . . . . . . . .14,17,18,25,26,. . . . . .
. . . . . . . . .15,16,19,24,27,. . . . . .
. . . . . . . . . . . .20,23,28,33,34,. . .
. . . . . . . . . . . .21,22,29,32,35,. . .
. . . . . . . . . . . . . . ,30,31,36,. . .
. . . . . . . . . . . . . . . . . .37,. . .
		

Crossrefs

A162800 a(n) = n-th grid point that is covered by the zig-zag function for prime numbers such that the grid point is a vertex in the graph of the function.

Original entry on oeis.org

0, 2, 4, 6, 9, 12, 15, 18, 21, 26, 30, 34, 39, 42, 45, 50, 56, 60, 64, 69, 72, 76, 81, 86, 93, 99, 102, 105, 108, 111, 120, 129, 134, 138, 144, 150, 154, 160, 165, 170, 176, 180, 186, 192, 195, 198, 205, 217, 225, 228, 231, 236, 240, 246, 254, 260, 266, 270, 274, 279
Offset: 0

Views

Author

Omar E. Pol, Jul 16 2009

Keywords

Comments

Also {0, 2} together the numbers A024675.
See A162345 for the first differences.

Crossrefs

Programs

  • Mathematica
    Join[{0, 2}, Most[#] + Differences[#]/2] & [Prime[Range[2, 100]]] (* Paolo Xausa, Jun 17 2024 *)

Extensions

Edited by Omar E. Pol, Jul 18 2009

A115061 a(n) is the number of occurrences of the n-th prime number in A051697.

Original entry on oeis.org

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

Views

Author

Lekraj Beedassy, Mar 01 2006

Keywords

Comments

Except for the second entry, the sequence also holds with respect to A077018.
a(n) equals A162345(n) for n>1 and equals A052288(n-2) for n>2. - Nathaniel Johnston, Jun 25 2011

Examples

			The 5th prime number, 11, appears three times in A051697. Therefore a(5) = 3.
		

Programs

  • Mathematica
    a = {3}; For[n = 2, n < 100, n++, c = 0; For[j = Prime[n - 1], j < Prime[n + 1], j++, If[j < Prime[n], If[Prime[n] - j < j - Prime[n - 1], c++ ], If[Not[Prime[n + 1] - j < j - Prime[n]], c++ ]]]; AppendTo[a, c]]; a

Formula

a(n) = (prime(n+1) - prime(n-1))/2 for n>=3. - Nathaniel Johnston, Jun 25 2011

Extensions

Edited and extended by Stefan Steinerberger, Oct 27 2007

A162801 Bisection of A162800.

Original entry on oeis.org

0, 4, 9, 15, 21, 30, 39, 45, 56, 64, 72, 81, 93, 102, 108, 120, 134, 144, 154, 165, 176, 186, 195, 205, 225, 231, 240, 254, 266, 274, 282, 300, 312, 324, 342, 351, 363, 376, 386, 399, 414, 426, 436, 446, 459, 465, 483, 495, 506, 522, 544, 560, 570, 582, 596
Offset: 1

Views

Author

Omar E. Pol, Jul 16 2009

Keywords

Comments

Essentially the same as A058296.

Crossrefs

A162802 Bisection of A162800.

Original entry on oeis.org

2, 6, 12, 18, 26, 34, 42, 50, 60, 69, 76, 86, 99, 105, 111, 129, 138, 150, 160, 170, 180, 192, 198, 217, 228, 236, 246, 260, 270, 279, 288, 309, 315, 334, 348, 356, 370, 381, 393, 405, 420, 432, 441, 453, 462, 473, 489, 501, 515, 532, 552, 566, 574, 590, 600
Offset: 1

Views

Author

Omar E. Pol, Jul 16 2009

Keywords

Comments

Also, 2 together with the numbers A079424.

Crossrefs

Showing 1-7 of 7 results.