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 1-10 of 19 results. Next

A162689 Strictly positive numbers n such that (18*n)/(18+n) are integers.

Original entry on oeis.org

9, 18, 36, 63, 90, 144, 306
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 10 2009

Keywords

Comments

The 18th row of A127730.
The ansatz 18*n/(18+n)=j (any integer j) yields n=18*j/(18-j) which demonstrates that the sequence is finite if n>=0. [R. J. Mathar, Jul 13 2009]

Crossrefs

Cf. A162688
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=18;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]],AppendTo[lst,n]],{n,9!}];lst
Select[Range[400],IntegerQ[(18#)/(18+#)]&] (* Harvey P. Dale, Nov 12 2011 *)

Extensions

Edited by R. J. Mathar, Jul 13 2009

A162690 Strictly positive numbers n such that 20*n/(20+n) are integers.

Original entry on oeis.org

5, 20, 30, 60, 80, 180, 380
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 10 2009

Keywords

Comments

The 20th row of A127730.
The ansatz 20*n/(20+n)=j (any integer j) yields n=20*j/(20-j) which demonstrates that the sequence is finite if n>=0. [R. J. Mathar, Jul 13 2009]

Crossrefs

Cf. A162688, A162689
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=20;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]], AppendTo[lst,n]],{n,9!}];lst

Extensions

Edited by R. J. Mathar, Jul 13 2009

A162691 Strictly positive numbers n such that 24*n/(24+n) is an integer.

Original entry on oeis.org

8, 12, 24, 40, 48, 72, 120, 168, 264, 552
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 10 2009

Keywords

Comments

The 24th row of A127730.
The ansatz 24*n/(24+n)=j (any integer j) yields n=24*j/(24-j) which demonstrates that the sequence is finite if n>=0. [R. J. Mathar, Jul 13 2009]

Crossrefs

Cf. A162688, A162689, A162690
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=24;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]],AppendTo[lst,n]],{n,9!}];lst
Select[Range[600],IntegerQ[(24#)/(24+#)]&] (* Harvey P. Dale, Jul 30 2021 *)

Extensions

Edited by R. J. Mathar, Jul 13 2009

A162692 Strictly positive numbers n such that 28*n/(28+n) are integers.

Original entry on oeis.org

21, 28, 70, 84, 168, 364, 756
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 10 2009

Keywords

Comments

The 28th row of A127730.
The ansatz 28*n/(28+n)=j (any integer j) yields n=28*j/(28-j) which demonstrates that the sequence is finite if n>=0. [R. J. Mathar, Jul 13 2009]

Crossrefs

Cf. A162688, A162689, A162690, A162691
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=28;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]],AppendTo[lst,n]],{n,9!}];lst

Extensions

Edited by R. J. Mathar, Jul 13 2009

A162693 Strictly positive numbers n such that 30*n/(30+n) are integers.

Original entry on oeis.org

6, 15, 20, 30, 45, 60, 70, 120, 150, 195, 270, 420, 870
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 10 2009

Keywords

Comments

The 30th row of A127730.
The ansatz 30*n/(30+n)=j (any integer j) yields n=30*j/(30-j) which demonstrates that the sequence is finite if n>=0. [R. J. Mathar, Jul 13 2009]

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=30;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]],AppendTo[lst,n]],{n,9!}];lst
Select[Range[1000],IntegerQ[(30#)/(30+#)]&] (* Harvey P. Dale, Sep 25 2019 *)

Extensions

Edited by R. J. Mathar, Jul 13 2009

A162694 Strictly positive numbers n such that 36*n/(36+n) are integers.

Original entry on oeis.org

12, 18, 36, 45, 72, 108, 126, 180, 288, 396, 612, 1260
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 10 2009

Keywords

Comments

The 36th row of A127730.
The ansatz 36*n/(36+n) = j (any integer j) yields n = 36*j/(36-j) which demonstrates that the sequence is finite if n >= 0. - R. J. Mathar, Jul 13 2009
Positive integers n such that half of the harmonic mean of 36 and n is an integer. - Wesley Ivan Hurt, Sep 07 2014

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692, A162693
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    Select[Range[1000], IntegerQ[36#/(36 + #)] &] (* Alonso del Arte, Sep 06 2014 *)

Extensions

Edited by R. J. Mathar, Jul 13 2009

A162817 Positive numbers n such that 40*n/(40+n) are integers.

Original entry on oeis.org

10, 24, 40, 60, 120, 160, 280, 360, 760, 1560
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 13 2009

Keywords

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692, A162693, A162694
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=40;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]], AppendTo[lst,n]],{n,9!}];lst
Select[Range[1600],IntegerQ[(40#)/(40+#)]&] (* Harvey P. Dale, Oct 11 2011 *)

Extensions

Keywords fini,full added by R. J. Mathar, Jul 31 2009

A162818 Strictly positive numbers n such that (42*n)/(42+n) is an integer.

Original entry on oeis.org

7, 21, 42, 56, 84, 105, 154, 210, 252, 399, 546, 840, 1722
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 13 2009

Keywords

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692, A162693, A162694, A162817
Cf. A127730 - Franklin T. Adams-Watters, Aug 07 2009

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=42;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]],AppendTo[lst,n]],{n,9!}];lst
Select[Range[2000], Divisible[42 #, 42 + #] &] (* Harvey P. Dale, May 09 2012 *)

Extensions

Keywords fini and full added by Franklin T. Adams-Watters, Aug 07 2009

A162819 Positive numbers n such that 48*n/(48+n) are integers.

Original entry on oeis.org

16, 24, 48, 80, 96, 144, 208, 240, 336, 528, 720, 1104, 2256
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 13 2009

Keywords

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692, A162693, A162694, A162817, A162818
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=48;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]], AppendTo[lst,n]],{n,9!}];lst
Select[Range[2300],IntegerQ[(48#)/(48+#)]&] (* Harvey P. Dale, Dec 18 2018 *)

Extensions

Keywords fini,full added by R. J. Mathar, Jul 31 2009

A162820 Positive numbers n such that 60*n/(60+n) are integers.

Original entry on oeis.org

12, 15, 20, 30, 40, 60, 84, 90, 120, 140, 165, 180, 240, 300, 340, 390, 540, 660, 840, 1140, 1740, 3540
Offset: 1

Views

Author

Vladimir Joseph Stephan Orlovsky, Jul 13 2009

Keywords

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692, A162693, A162694, A162817, A162818, A162819
Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

  • Mathematica
    f[a_,b_]:=(a*b)/(a+b); a=60;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]], AppendTo[lst,n]],{n,9!}];lst

Extensions

Keywords fini,full added by R. J. Mathar, Jul 31 2009
Showing 1-10 of 19 results. Next

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