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 1-3 of 3 results.

A163497 Numbers n with following property: let c = nearest cube to n that is different from n and let p = nearest prime to n that is different from n. Then |n-c| = |n-p|.

Original entry on oeis.org

2, 25, 28, 119, 126, 340, 345, 728, 731, 1329, 1346, 2188, 2200, 3374, 3382, 4911, 4916, 6858, 6861, 9259, 9269, 12165, 12182, 15622, 15627, 19682, 19685, 24384, 24390, 29790, 29797, 35935, 35944, 42869, 42887, 50652, 50662, 59300, 59326
Offset: 1

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Author

Gaurav Kumar, Jul 29 2009

Keywords

Comments

With the exception of 2 those k where A051699(k) = A074989(k) (same distance to nearest prime and to nearest cube). - R. J. Mathar, Aug 08 2009

Examples

			a(1) = 2 since 2 lies between 1 (cube) and 3 (prime);
a(2) = 28 since 28 lies between 27 (cube) and 29 (prime).

Crossrefs

Cf. A154840.

Programs

  • Maple
    A163497 := proc(n) option remember ; local a; if n = 1 then 2; else for a from procname(n-1)+1 do if A051699(a) = A074989(a) then return a; end if; end do ; end if; end proc: # R. J. Mathar, Nov 01 2009

Extensions

Edited by Zak Seidov, Aug 01 2009
Further edited by N. J. A. Sloane, Oct 31 2009

A333884 Difference between smallest cube > n and n.

Original entry on oeis.org

1, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 08 2020

Keywords

Comments

a(n) is the smallest positive number k such that n + k is a cube.

Links

Crossrefs

Cf. A000578, A048763, A055400, A068527, A080883, A154840.

Programs

  • Mathematica
    Table[Floor[n^(1/3) + 1]^3 - n, {n, 0, 80}]

Formula

a(n) = floor(n^(1/3) + 1)^3 - n.

A289642 Number of 2-digit numbers whose digits add up to n.

Original entry on oeis.org

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

Views

Author

Miquel Cerda, Jul 09 2017

Keywords

Comments

The 2-digit numbers distributed according to the sum of their digits n.
Symmetrical sequence; a(n) = a(19 - n).

Examples

			n(5) = 5 because there are 5 numbers whose digits sum = 5 (14, 23, 32, 41, 50).

Crossrefs

Cf. A071817 (3-digit numbers), A090579 (4-digit numbers), A090580 (5-digit numbers), A090581 (6-digit numbers), A278969 (7-digit numbers), A278971 (8-digit numbers), A289354 (9-digit numbers), A053188, A074989, A004739, A066635, A154840, A249121.

Formula

G.f.: (1 - x^10)*(x - x^10)/(1 - x)^2.
a(n) = (19-abs(n-9)-abs(n-10))/2 for n=1..18. - Wesley Ivan Hurt, Jul 09 2017
Showing 1-3 of 3 results.

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

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