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 1-7 of 7 results.

A057100 Hypotenuses of Pythagorean triangles (ordered by the product of the sides).

Original entry on oeis.org

5, 10, 13, 15, 17, 20, 25, 26, 25, 29, 30, 41, 37, 34, 35, 39, 40, 50, 61, 45, 52, 51, 50, 65, 53, 55, 85, 58, 65, 60, 75, 82, 65, 74, 68, 65, 70, 78, 113, 73, 101, 75, 85, 80, 85, 91, 100, 89, 85, 122, 87, 90, 145, 123, 104, 95, 111, 102, 97, 100, 145, 130, 125, 106
Offset: 1

Views

Author

Henry Bottomley, Aug 01 2000

Keywords

Examples

			a(1)=5 since 3*4*5=60 is smallest possible positive product
		

Crossrefs

Programs

  • Mathematica
    maxShortLeg = 66; terms = 64;
    r[a_] := {a, b, c} /. {ToRules[Reduce[a <= b < c && a^2+b^2 == c^2, {b, c}, Integers]]};
    abc = r /@ Complement[Range[maxShortLeg], {1, 2, 4}] // Flatten[#, 1]&;
    SortBy[abc, Times @@ # &][[;; terms, 3]] (* Jean-François Alcover, Nov 21 2019 *)

Formula

a(n) =A057096(n)/(A057098(n)*A057099(n)) =sqrt(A057098(n)^2+A057099(n)^2)

A063011 Ordered products of the sides of primitive Pythagorean triangles.

Original entry on oeis.org

60, 780, 2040, 4200, 12180, 14760, 15540, 40260, 65520, 66780, 92820, 120120, 189840, 192720, 199980, 235620, 277680, 354960, 453960, 497640, 595140, 619020, 643500, 1021020, 1063860, 1075620, 1265880, 1484340, 1609080, 1761540
Offset: 1

Views

Author

Henry Bottomley, Jul 26 2001

Keywords

Comments

It is an open question whether any two distinct Pythagorean triples can have the same product of their sides.

Examples

			a(1)=3*4*5=60; a(2)=5*12*13=780 (rather than 6*8*10=480, which would not be primitive).
		

Crossrefs

Programs

  • Mathematica
    k=17000000;lst={};Do[Do[If[IntegerQ[a=Sqrt[c^2-b^2]]&&GCD[a,b,c]==1,If[a>=b,Break[]];x=a*b*c;If[x<=k,AppendTo[lst,x]]],{b,c-1,4,-1}],{c,5,700,1}];Union@lst (* Vladimir Joseph Stephan Orlovsky, Sep 05 2009 *)
    With[{nn=50},Take[(Times@@#)Sqrt[#[[1]]^2+#[[2]]^2]&/@Union[Sort/@ ({Times@@#, (Last[#]^2-First[#]^2)/2}&/@(Select[Subsets[Range[1,nn+1,2],{2}],GCD@@#==1&]))]//Union,nn]] (* Harvey P. Dale, Jun 08 2018 *)

A057098 Shortest side of a Pythagorean triangle (ordered by the product of the sides).

Original entry on oeis.org

3, 6, 5, 9, 8, 12, 7, 10, 15, 20, 18, 9, 12, 16, 21, 15, 24, 14, 11, 27, 20, 24, 30, 16, 28, 33, 13, 40, 25, 36, 21, 18, 33, 24, 32, 39, 42, 30, 15, 48, 20, 45, 36, 48, 40, 35, 28, 39, 51, 22, 60, 54, 17, 27, 40, 57, 36, 48, 65, 60, 24, 32, 35, 56, 63, 45, 60, 19, 66, 44, 56
Offset: 1

Views

Author

Henry Bottomley, Aug 01 2000

Keywords

Examples

			a(1)=3 since 3*4*5=60 is smallest possible positive product
		

Crossrefs

Programs

  • Mathematica
    maxShortLeg = 66; terms = 71;
    r[a_] := {a, b, c} /. {ToRules[Reduce[a <= b < c && a^2+b^2 == c^2, {b, c}, Integers]]};
    abc = r /@ Complement[Range[maxShortLeg], {1, 2, 4}] // Flatten[#, 1]&;
    SortBy[abc, Times @@ # &][[;; terms, 1]] (* Jean-François Alcover, Nov 21 2019 *)

Formula

a(n) =A057096(n)/(A057099(n)*A057100(n)) =sqrt(A057100(n)^2-A057099(n)^2)

A057099 Middle side of a Pythagorean triangle (ordered by the product of the sides).

Original entry on oeis.org

4, 8, 12, 12, 15, 16, 24, 24, 20, 21, 24, 40, 35, 30, 28, 36, 32, 48, 60, 36, 48, 45, 40, 63, 45, 44, 84, 42, 60, 48, 72, 80, 56, 70, 60, 52, 56, 72, 112, 55, 99, 60, 77, 64, 75, 84, 96, 80, 68, 120, 63, 72, 144, 120, 96, 76, 105, 90, 72, 80, 143, 126, 120, 90, 84, 108, 91
Offset: 1

Views

Author

Henry Bottomley, Aug 01 2000

Keywords

Examples

			a(1)=4 since 3*4*5=60 is smallest possible positive product
		

Crossrefs

Programs

  • Mathematica
    maxShortLeg = 66; terms = 67;
    r[a_] := {a, b, c} /. {ToRules[Reduce[a <= b < c && a^2+b^2 == c^2, {b, c}, Integers]]};
    abc = r /@ Complement[Range[maxShortLeg], {1, 2, 4}] // Flatten[#, 1]&;
    SortBy[abc, Times @@ # &][[;; terms, 2]] (* Jean-François Alcover, Nov 21 2019 *)

Formula

a(n) =A057096(n)/(A057098(n)*A057100(n)) =sqrt(A057100(n)^2-A057098(n)^2)

A057097 Products of the three sides of Pythagorean triangles divided by 60.

Original entry on oeis.org

1, 8, 13, 27, 34, 64, 70, 104, 125, 203, 216, 246, 259, 272, 343, 351, 512, 560, 671, 729, 832, 918, 1000, 1092, 1113, 1331, 1547, 1624, 1625, 1728, 1890, 1968, 2002, 2072, 2176, 2197, 2744, 2808, 3164, 3212, 3333, 3375, 3927, 4096, 4250, 4459, 4480
Offset: 1

Views

Author

Henry Bottomley, Aug 01 2000

Keywords

Comments

Note that if m appears in the sequence then k^3*m will also appear for all k and so in particular all cubes appear; the reverse is not always true (for example, 32*255*257/60 = 34952 = 2^3*4369 eventually appears, but 4369 does not).
By considering the Pythagorean triangle (3k, 4k, 5k) we see that all numbers k^3 are in the sequence. - Sergey Pavlov, Mar 29 2017

Examples

			a(1) = 3*4*5/60 = 1.
		

Crossrefs

Cf. A000578 (cubes).

Programs

  • Mathematica
    (k=600000; lst={}; Do[Do[If[IntegerQ[a=Sqrt[c^2 - b^2]], If[a>=b, Break[]]; x=a b c; If[x<=k, AppendTo[lst, x]]], {b, c - 1, 4, -1}], {c, 5, 400, 1}]; Union@lst)/60 (* Vincenzo Librandi Mar 30 2017 *)

Formula

a(n) = A057096(n)/60 = A057098(n)*A057099(n)*A057100(n)/60.

A081779 Ordered m for which m = k^3*a*b*(a^4 - b^4) determine (unique) solution triples(k,a,b), where k=1,2,3,... and (a,b) are coprime pairs, not both odd (i.e., of opposite parity).

Original entry on oeis.org

30, 240, 390, 810, 1020, 1920, 2100, 3120, 3750, 6090, 6480, 7380, 7770, 8160, 10290, 10530, 15360, 16800, 20130, 21870, 24960, 27540, 30000, 32760, 33390, 39930, 46410, 48720, 48750, 51840, 56700, 59040, 60060, 62160, 65280, 65910, 82320, 84240, 94920, 96360
Offset: 1

Views

Author

Lekraj Beedassy, Apr 10 2003

Keywords

Comments

Also called Saint-Exupery numbers.

Crossrefs

Cf. A057096.

Programs

Formula

a(n) = A057096(n)/2.

Extensions

Corrected and extended by Jean-François Alcover, Nov 21 2019

A057101 Area of a Pythagorean triangle (ordered by the product of the sides).

Original entry on oeis.org

6, 24, 30, 54, 60, 96, 84, 120, 150, 210, 216, 180, 210, 240, 294, 270, 384, 336, 330, 486, 480, 540, 600, 504, 630, 726, 546, 840, 750, 864, 756, 720, 924, 840, 960, 1014, 1176, 1080, 840, 1320, 990, 1350, 1386, 1536, 1500, 1470, 1344, 1560, 1734, 1320
Offset: 1

Views

Author

Henry Bottomley, Aug 01 2000

Keywords

Examples

			a(1)=3*4/2=6 since 3*4*5=60 is smallest possible positive product
		

Crossrefs

Formula

a(n) =A057096(n)/(2*A057100(n)) =A057098(n)*A057099(n)/2
Showing 1-7 of 7 results.