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 1-5 of 5 results.

A116133 Numbers k such that k concatenated with k-4 gives the product of two numbers which differ by 9.

Original entry on oeis.org

64, 1876, 3214, 8776, 17227120144584448354, 19391087990479091186, 21557280540171744040, 23970390649400564404, 26051259424903756364, 28697643366269876506, 31320461807899711990, 34215988012600009664
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Comments

Also numbers k such that k concatenated with k+4 gives the product of two numbers which differ by 7.
Since k*(10^j+1) + 4 = m*(m+7) iff k*(10^j+1) - 4 = m*(m+7) - 8 = (m-1)*(m+8) = M*(M+9) this is trivially the same sequence. - N. J. A. Sloane, Apr 11 2007

Examples

			8776//8772 = 9364 * 9373, where // denotes concatenation. Also 8776//8780 = 9365 * 9372.
		

Crossrefs

Extensions

Edited by N. J. A. Sloane, Apr 11 2007

A116320 n times n+8 gives the concatenation of two numbers m and m+4.

Original entry on oeis.org

4, 86, 32762, 67231, 76322, 693956, 900097, 7295105, 9068525, 3664355432, 6335644561, 8015841979, 8419801579, 9900000997, 3252382148828, 6747617851165, 7253863787097, 9474890578438, 9981136514370
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Comments

Includes 10^(4*k+2)-10^(3*k+2)+10^(k+1)-3 for k >= 1. - Robert Israel, Jun 20 2018

Crossrefs

Programs

  • Maple
    Res:= NULL: count:= 0:
    for d from 1 while count < 100 do
      R:= sort(select(t -> t^2 + 8*t - 4 > 10^(2*d-1) and t^2+8*t-4 < 10^(2*d), map(t -> rhs(op(t)), [msolve(n^2+8*n-4, 10^d+1)])));
      count := count+nops(R);
      Res:= Res, op(R);
    od:
    Res; # Robert Israel, Jun 20 2018

A116311 Numbers k such that k*(k+7) gives the concatenation of two numbers m and m+3.

Original entry on oeis.org

8445, 8810, 69125298546226023971, 69855225553525294044, 74604750601020544519, 75334677608319814592, 92496418993920707746, 93226346001219977819, 97975871048715228294, 98705798056014498367
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Examples

			8810 * 8817 = 7767//7770, where // denotes concatenation.
		

Crossrefs

A116318 n times n+6 gives the concatenation of two numbers m and m+4.

Original entry on oeis.org

32, 63, 45211540, 54788455, 78317867, 72388446037855609175404257, 73247326752475247326752672, 75267524732673267524732472, 76126405447292905676080887, 42053270820132695893502981749303
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Examples

			78317867 * 78317873 = 61336887//61336891, where // denotes
concatenation.
		

Crossrefs

A116326 Numbers k such that k*(k+7) gives the concatenation of two numbers m and m+5.

Original entry on oeis.org

8601, 9423, 35441, 64553, 73644, 4851412, 5148582, 8784946, 726216462985, 753613723259, 791909893642, 819307153916, 3654754464602947513, 4527063717215234299, 5472936282784765695, 6345245535397052481
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Examples

			8784946 * 8784953 = 7717533//7717538, where // denotes concatenation.
		

Crossrefs

Showing 1-5 of 5 results.