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.

A348640 Denominators of the remainders in the greedy Egyptian fraction representation of 1 with square denominators (A348626).

Original entry on oeis.org

1, 4, 2, 4, 36, 36, 1764, 2352, 115248, 416333400, 107225418169800, 562904175532925098845000, 1857180475556752726157213892231405000, 424594887903818740281781489141947299544299873193026842805000, 27616236678198713245845367246922973802897093015095664467139174240964043973815461112656369429045000
Offset: 0

Views

Author

Max Alekseyev, Oct 26 2021

Keywords

Comments

a(n) divides LCM( A348626(1), ..., A348626(n) )^2.

Examples

			The first few remainders are 1, 3/4, 1/2, 1/4, 5/36, 1/36, 13/1764, 1/2352, 1/115248, 11/416333400, ... - _N. J. A. Sloane_, Apr 21 2025
		

Crossrefs

Cf. A000058, A348626, A348641 (numerators), A382719.

Programs

  • PARI
    s=1; for(n=1, 20, print1(denominator(s), ", "); t=sqrtint(floor(1/s))+1; s-=1/t^2);

Formula

a(n) = denominator of 1 - Sum_{k=1..n} 1/A348626(k)^2.

A348641 Numerators of the remainders in the greedy Egyptian fraction representation of 1 with square denominators (A348626).

Original entry on oeis.org

1, 3, 1, 1, 5, 1, 13, 1, 1, 11, 817, 10252633, 100287877217, 6528073355352461938177, 62417959978427831731164878741347502689913, 70288410375198910851231147751405037331087262102769745506188780420713, 1637848790982120651632223869737258212156187623721099799629950249330321081907360495884020503587938103781073751577
Offset: 0

Views

Author

Max Alekseyev, Oct 26 2021

Keywords

Examples

			The first few remainders are 1, 3/4, 1/2, 1/4, 5/36, 1/36, 13/1764, 1/2352, 1/115248, 11/416333400, ... - _N. J. A. Sloane_, Apr 21 2025
		

Crossrefs

Cf. A000058, A348626, A348640 (denominators), A382719.

Programs

  • PARI
    s=1; for(n=1, 20, print1(numerator(s), ", "); t=sqrtint(floor(1/s))+1; s-=1/t^2);

Formula

a(n) = numerator of 1 - Sum_{k=1..n} 1/A348626(k)^2.

A382719 Numerator of Sum_{i=1..n} 1/A348626(i)^2.

Original entry on oeis.org

0, 1, 1, 3, 31, 35, 1751, 2351, 115247, 416333389, 107225418168983, 562904175532925088592367, 1857180475556752726157213791943527783, 424594887903818740281781489141947299537771799837674380866823, 27616236678198713245845367246922973802897093015095664467076756280985616142084296233915021926355087
Offset: 0

Views

Author

N. J. A. Sloane, Apr 21 2025

Keywords

Comments

The denominators are given in A348640.

Examples

			The first few fractions are 0, 1/4, 1/2, 3/4, 31/36, 35/36, 1751/1764, 2351/2352, 115247/115248, 416333389/416333400, ...
		

Crossrefs

Formula

a(n) = A348640(n) - A348641(n).

A348625 Number of Egyptian fractions with squared denominators: number of solutions to the equation 1 = 1/x_1^2 + ... + 1/x_n^2 with 0 < x_1 <= ... <= x_n.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 1, 4, 7, 47, 186, 1809, 27883
Offset: 1

Views

Author

Max Alekseyev, Oct 25 2021

Keywords

Comments

All denominators are bounded by A348626(n), i.e., 0 < x_1 <= ... <= x_n < A348626(n). Furthermore, for a fixed n, x_i <= sqrt(n+1-i)*(A348626(i)-1).

Crossrefs

A369607 Greedy solution a(1) < a(2) < ... to 1/a(1) + 1/a(2) + ... = (1 - 1/a(1)) * (1 - 1/a(2)) * ....

Original entry on oeis.org

3, 6, 29, 803, 643727, 414383582243, 171713753231982206218247, 29485613049014079571725771288849499850026859243, 869401376876189366008603664962520703088459987798626788985159595026678611496977754082506135887
Offset: 1

Views

Author

Max Alekseyev, Jan 27 2024

Keywords

Comments

For any n, (x1, x2, ..., xn) = (a(1), a(2), ..., a(n-1), a(n)-1) forms a solution to 1/x1 + ... + 1/xn = (1 - 1/x1) * ... * (1 - 1/xn), proving that A369470(n) >= A369469(n) >= 1.

Crossrefs

Formula

a(n+2) = a(n+1)^2 + (a(n) - 2)*a(n+1) - a(n)^3 + 2*a(n)^2 - 2*a(n) + 2.
Showing 1-5 of 5 results.