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 1-4 of 4 results.

A072579 In binary representation: k has the same number of 1's as the k-th prime has 0's.

Original entry on oeis.org

1, 7, 13, 26, 37, 41, 42, 45, 49, 50, 58, 59, 62, 69, 70, 74, 78, 79, 87, 103, 105, 107, 110, 114, 118, 121, 134, 139, 141, 142, 145, 147, 158, 161, 162, 164, 165, 168, 175, 185, 189, 198, 202, 203, 213, 214, 223, 227, 232, 234, 243, 267, 275, 282, 289, 292
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 23 2002

Keywords

Examples

			In binary representation 70 = '1000110' has three 1's and A000040(70) = 349 = '101011101' has three 1's: therefore 70 is a term.

Links

Crossrefs

Cf. A000120, A023416, A035103, A049084, A071600, A072577, A072578, A072582.

Programs

  • Mathematica
    Select[Range[300],DigitCount[#,2,1]==DigitCount[Prime[#],2,0]&] (* Harvey P. Dale, May 02 2012 *)

Formula

A023416(A072582(n)) = A000120(a(n)) = A035103(n).
a(n) = A049084(A072582(n)).

A072580 a(n) = A000040(A072577(n)).

Original entry on oeis.org

11, 13, 71, 79, 89, 107, 127, 131, 139, 157, 179, 181, 227, 229, 331, 337, 419, 421, 433, 457, 461, 487, 491, 787, 797, 809, 811, 821, 823, 853, 877, 919, 977, 1163, 1181, 1213, 1223, 1231, 1277, 1279, 1459, 1487, 1523, 1667, 1697, 1733, 1741, 1861, 1867
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 23 2002

Keywords

Examples

			In binary representation 20 and A000040(20) = 71 have three 0's: 13 = '10100' and 71 = '1000111', therefore 71 is a term.

Links

Crossrefs

Cf. A000040, A023416, A035103, A072439, A072577, A072581, A072582, A072584.

Programs

  • Mathematica
    With[{m = 300}, Select[Transpose[{Range[m], Prime[Range[m]]}], Equal @@ DigitCount[#, 2, 0] &]][[;; , 2]] (* Amiram Eldar, Jul 27 2025 *)

Formula

A023416(a(n)) = A023416(A072577(n)) = A035103(n).

A072581 a(n) = A000040(A072578(n)).

Original entry on oeis.org

19, 53, 139, 193, 311, 313, 409, 577, 641, 719, 787, 809, 1033, 1061, 1097, 1171, 1193, 1289, 1627, 1637, 1657, 1669, 1693, 1699, 1747, 1811, 1877, 1889, 2083, 2089, 2153, 2161, 2179, 2203, 2213, 2273, 2311, 2659, 2689, 2753, 3169, 3677, 3727, 3733
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 23 2002

Keywords

Examples

			In binary representation 80 = '1010000' has five 0's and A000040(80) = 409 = '110011001' has five 1's: therefore 409 is a term.

Links

Crossrefs

Cf. A000040, A000120, A014499, A023416, A072439, A072578, A072580, A072582, A072584.

Programs

  • Mathematica
    With[{m = 600}, Select[Transpose[{Range[m], Prime[Range[m]]}], DigitCount[First[#], 2, 0] == DigitCount[Last[#], 2, 1] &]][[;; , 2]] (* Amiram Eldar, Jul 28 2025 *)

Formula

A000120(a(n)) = A023416(A072578(n)) = A014499(n).

A072584 a(n) = A000040(A072583(n)).

Original entry on oeis.org

3, 7, 23, 29, 31, 37, 43, 47, 59, 61, 103, 109, 137, 149, 151, 163, 167, 173, 191, 199, 223, 233, 239, 241, 251, 257, 263, 307, 317, 359, 367, 379, 383, 431, 439, 443, 463, 467, 479, 499, 503, 509, 541, 557, 569, 599, 607, 613, 617, 631, 643, 653, 659, 673
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 23 2002

Keywords

Links

Crossrefs

Cf. A000040, A072439, A072580, A072581, A072582, A072583.

Programs

  • Mathematica
    With[{m = 120}, Select[Transpose[{Range[m], Prime[Range[m]]}], Intersection @@ DigitCount[#, 2] == {} &]][[;; , 2]] (* Amiram Eldar, Jul 28 2025 *)
Showing 1-4 of 4 results.

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