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.

A221942 a(n) = floor(sqrt(5*2^n)).

Original entry on oeis.org

2, 3, 4, 6, 8, 12, 17, 25, 35, 50, 71, 101, 143, 202, 286, 404, 572, 809, 1144, 1619, 2289, 3238, 4579, 6476, 9158, 12952, 18317, 25905, 36635, 51810, 73271, 103621, 146542, 207243, 293085, 414486, 586171, 828972, 1172343, 1657944, 2344687, 3315888, 4689374, 6631776, 9378748, 13263553, 18757497, 26527107
Offset: 0

Views

Author

N. J. A. Sloane, Feb 01 2013

Keywords

Comments

Theorem 3 of Dubickas implies that infinitely many terms of this sequence are divisible by 2 or 3 (and hence infinitely many composites). - Charles R Greathouse IV, Feb 04 2016

References

  • Artūras Dubickas, Prime and composite integers close to powers of a number, Monatsh. Math. 158:3 (2009), pp. 271-284.

Links

Crossrefs

Cf. A017910, A017913, A017919, A114183, A221718, A221942-A221946.

Programs

A221944 Floor(sqrt(2*3^n)).

Original entry on oeis.org

1, 2, 4, 7, 12, 22, 38, 66, 114, 198, 343, 595, 1030, 1785, 3092, 5357, 9278, 16071, 27835, 48213, 83507, 144639, 250523, 433919, 751571, 1301759, 2254713, 3905277, 6764139, 11715833, 20292418, 35147500, 60877256, 105442501, 182631769, 316327504, 547895309, 948982513, 1643685929, 2846947541, 4931057788
Offset: 0

Views

Author

N. J. A. Sloane, Feb 01 2013

Keywords

Links

Crossrefs

Cf. A017910, A017913, A017919, A114183, A221718, A221942-A221946.

Programs

A221945 a(n) = floor(sqrt(2*5^n)).

Original entry on oeis.org

1, 3, 7, 15, 35, 79, 176, 395, 883, 1976, 4419, 9882, 22097, 49410, 110485, 247052, 552427, 1235264, 2762135, 6176323, 13810679, 30881617, 69053396, 154408088, 345266983, 772040444, 1726334915, 3860202221, 8631674575, 19301011109, 43158372875, 96505055547, 215791864375, 482525277735
Offset: 0

Views

Author

N. J. A. Sloane, Feb 01 2013

Keywords

Comments

Floor of norm of (1 + i) * (1 + 2i)^n. - Jon Perry, Dec 06 2013

Links

Crossrefs

Cf. A017910, A017913, A017919, A114183, A221718, A221942-A221946.

Programs

A221943 Floor(sqrt(7*2^n)).

Original entry on oeis.org

2, 3, 5, 7, 10, 14, 21, 29, 42, 59, 84, 119, 169, 239, 338, 478, 677, 957, 1354, 1915, 2709, 3831, 5418, 7662, 10836, 15325, 21673, 30651, 43347, 61303, 86695, 122606, 173391, 245213, 346783, 490426, 693567, 980853, 1387135, 1961706, 2774271, 3923412, 5548542, 7846824, 11097085, 15693648, 22194170, 31387297
Offset: 0

Views

Author

N. J. A. Sloane, Feb 01 2013

Keywords

Comments

Theorem 3 of Dubickas implies that infinitely many terms of this sequence are divisible by 2 or 3 (and hence infinitely many composites). - Charles R Greathouse IV, Feb 04 2016

References

  • Artūras Dubickas, Prime and composite integers close to powers of a number, Monatsh. Math. 158:3 (2009), pp. 271-284.

Crossrefs

Cf. A017910, A017913, A017919, A114183, A221718, A221942-A221946.

Programs

  • Mathematica
    Floor[Sqrt[7*2^Range[0,50]]] (* Harvey P. Dale, Apr 11 2018 *)
  • PARI
    a(n)=sqrtint(7<Charles R Greathouse IV, Apr 18 2013
Showing 1-4 of 4 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.