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

A298044 1/16 of the edge with the largest 2-adic valuation of a primitive 3-simplex (0, b=A031173, c=A031174, d=A031175).

Original entry on oeis.org

15, 15, 30, 45, 10, 63, 99, 55, 52, 187, 195, 374, 33, 396, 418, 286, 510, 570, 572, 490, 221, 63, 273, 910, 1050, 1092, 660, 1160, 882, 885, 1148, 1485, 1505, 1092, 495, 1870, 308, 858, 1485, 585, 990, 385, 1333, 1001, 2907, 3045, 2277, 1394, 1475, 2310, 3690, 594, 3885, 3465, 2755, 1496, 4422, 2730, 3393
Offset: 1

Views

Author

Ralf Steiner, Jan 11 2018

Keywords

Comments

Each primitive 3-simplex (0,b,c,d) with b > c > d is built by an odd, an even and an edge with the largest 2-adic valuation.

Crossrefs

A298046 1/4 of the even edge of least 2-adic valuation of a primitive 3-simplex (0, b=A031173, c=A031174, d=A031175).

Original entry on oeis.org

11, 63, 35, 33, 198, 275, 255, 585, 660, 195, 207, 390, 1449, 187, 1575, 1683, 1222, 418, 741, 2457, 2805, 275, 3465, 270, 2574, 2205, 4437, 1518, 3850, 5369, 5940, 1225, 6171, 6426, 3808, 1950, 7695, 1890, 8901, 8976, 9275, 741, 6435, 297, 10395, 4615, 12831, 12870, 13299, 2133, 13570, 7843, 10593, 4901
Offset: 1

Views

Author

Ralf Steiner, Jan 11 2018

Keywords

Comments

Each primitive 3-simplex (0,b,c,d) with b > c > d is built by 1 odd edge and 2 even edges; the edge that is considered here is the even one with the least 2-adic valuation.

Crossrefs

A298047 The odd edge of a primitive 3-simplex (0, b=A031173, c=A031174, d=A031175).

Original entry on oeis.org

117, 275, 693, 85, 231, 1155, 187, 429, 855, 2475, 2035, 2295, 6325, 195, 1155, 1755, 495, 1575, 9405, 10725, 2925, 12075, 4901, 1881, 11753, 7579, 8789, 16929, 19305, 5643, 4599, 17157, 6435, 935, 26649, 23751, 10725, 35321, 35075, 1105, 2163, 38475, 38571, 39195, 5491, 15939, 51205, 24225, 9405, 57275
Offset: 1

Views

Author

Ralf Steiner, Jan 11 2018

Keywords

Comments

Each primitive 3-simplex (0,b,c,d) with b > c > d is built by 1 odd edge and 2 even edges; the edge that is considered here is the odd edge.

Crossrefs

A031174 Intermediate edge b of smallest (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).

Original entry on oeis.org

117, 252, 480, 132, 231, 1100, 1020, 880, 855, 2475, 2035, 2295, 5796, 748, 6300, 4576, 4888, 1672, 9152, 9828, 3536, 1100, 4901, 1881, 11753, 8820, 10560, 16929, 15400, 14160, 18368, 17157, 24080, 17472, 15232, 23751, 10725, 13728
Offset: 1

Views

Author

Keywords

Comments

Primitive means that gcd(a,b,c) = 1.
See A031173 for a list of the 3356 primitive bricks with c < b < a < 5*10^8. - Giovanni Resta, Mar 23 2014

References

  • Calculated by F. Helenius (fredh(AT)ix.netcom.com).

Crossrefs

A031175 Shortest edge c of (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).

Original entry on oeis.org

44, 240, 140, 85, 160, 1008, 187, 429, 832, 780, 828, 1560, 528, 195, 1155, 1755, 495, 1575, 2964, 7840, 2925, 1008, 4368, 1080, 10296, 7579, 8789, 6072, 14112, 5643, 4599, 4900, 6435, 935, 7920, 7800, 4928, 7560, 23760, 1105, 2163, 2964
Offset: 1

Views

Author

Keywords

Comments

Primitive means that gcd(a,b,c) = 1.
See A031173 for a list of the 3356 primitive bricks with c < b < a < 5*10^8. - Giovanni Resta, Mar 23 2014

References

  • Calculated by F. Helenius (fredh(AT)ix.netcom.com).

Crossrefs

A195816 Edge lengths of Euler bricks.

Original entry on oeis.org

44, 85, 88, 117, 132, 140, 160, 170, 176, 187, 195, 220, 231, 234, 240, 252, 255, 264, 275, 280, 308, 320, 340, 351, 352, 374, 390, 396, 420, 425, 429, 440, 462, 468, 480, 484, 495, 504, 510, 528, 550, 560, 561, 572, 585, 595, 616, 640, 660, 680, 693, 700
Offset: 1

Views

Author

Keywords

Comments

Euler bricks are cuboids all of whose edges and face-diagonals are integers.

Examples

			For n=1, the edges (a,b,c) are (240,117,44) and the diagonals (d(a,b),d(a,c),d(b,c)) are (267,244,125).
		

References

  • L. E. Dickson, History of the Theory of Numbers, vol. 2, Diophantine Analysis, Dover, New York, 2005.
  • P. Halcke, Deliciae Mathematicae; oder, Mathematisches sinnen-confect., N. Sauer, Hamburg, Germany, 1719, page 265.

Crossrefs

Programs

  • Mathematica
    ok[a_] := Catch[Block[{b, c, s}, s = Reduce[a^2 + b^2 == c^2 && b > 0 && c > 0, {b, c}, Integers]; If[s === False, Throw@ False, s = b /. List@ ToRules@ s]; Do[If[ IntegerQ@ Sqrt[s[[i]]^2 + s[[j]]^2], Throw@ True], {i, 2, Length@s}, {j, i - 1}]]; False]; Select[ Range[700], ok] (* Giovanni Resta, Nov 22 2018 *)

Formula

Integer edges a>b>c such that integer face-diagonals are d(a,b)=sqrt(a^2+b^2), d(a,c)=sqrt(a^2,c^2), d(b,c)=sqrt(b^2,c^2)

A118899 Surfaces of Euler bricks.

Original entry on oeis.org

87576, 334920, 350304, 391560, 693264, 788184, 993720, 1339680, 1401216, 1566240, 2189400, 2773056, 3014280, 3152736, 3524040, 3974880, 4205256, 4291224, 5358720, 5604864, 6239376, 6264960, 6881160, 7087080, 7093656, 8373000, 8757600, 8943480, 9789000, 10330080, 10596696, 11092224
Offset: 1

Views

Author

Giovanni Resta, May 05 2006

Keywords

Comments

An Euler brick is a cuboid with integer sides and integer face diagonals.

Examples

			87576 is the surface of the Euler brick with sides 240, 117 and 44, whose face diagonals are 267, 244 and 125.
		

Crossrefs

Extensions

More terms from Robin Visser, Jan 02 2024

A023185 Square of main diagonal of 3-dimensional box with coprime integer sides and integer face diagonals.

Original entry on oeis.org

73225, 196729, 543049, 706225, 730249, 3560089, 3584425, 6434041, 8392849, 14561209, 15686089, 40742425, 43508881, 69339625, 73878025, 85753369, 88450609, 90723169, 146947321, 148031689, 180998425, 216698161, 235198825, 273080809
Offset: 1

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Author

Keywords

Comments

Ordered by length of main diagonal. - Sean A. Irvine, May 26 2019

Crossrefs

A196943 Face-diagonal lengths of Euler bricks.

Original entry on oeis.org

125, 157, 244, 250, 267, 281, 314, 348, 365, 373, 375, 471, 488, 500, 534, 562, 625, 628, 696, 707, 725, 730, 732, 746, 750, 773, 785, 801, 808, 825, 843, 875, 942, 976, 979, 1000, 1037, 1044, 1068, 1095, 1099, 1119, 1124, 1125, 1193, 1220, 1250, 1256, 1335
Offset: 1

Views

Author

Keywords

Comments

Euler bricks are cuboids all of whose edges and face-diagonals are integers.
It is not known whether any Euler brick with space-diagonals that are integers exists.
825 is the only integer common to the sets of edge lengths and of face-diagonal lengths <= 1000 for Euler bricks.

Examples

			For n=1, the edges (a,b,c) are (240,117,44) and the face-diagonals (d(a,b),d(a,c),d(b,c)) are (267,244,125).
Note the pleasing factorizations of the edge-lengths of this least Euler brick: 240 = 15*4^2; 117 = 13*3^2; 44 = 11*2^2.
		

References

  • L. E. Dickson, History of the Theory of Numbers, vol. 2, Diophantine Analysis, Dover, New York, 2005.
  • P. Halcke, Deliciae Mathematicae; oder, Mathematisches sinnen-confect., N. Sauer, Hamburg, Germany, 1719, page 265.

Crossrefs

cf. A195816, A031173, A031174, A031175. Edge lengths of Euler bricks are A195816.

Formula

Integer edges a > b > c such that integer face-diagonals are d(a,b) = sqrt(a^2 + b^2), d(a,c) = sqrt(a^2 + c^2), d(b,c) = sqrt(b^2 + c^2).

A118900 Volumes of Euler bricks.

Original entry on oeis.org

1235520, 8078400, 9884160, 16632000, 29272320, 33359040, 46569600, 64627200, 79073280, 133056000, 154440000, 218116800, 234178560, 266872320, 302132160, 372556800, 423783360, 449064000, 517017600, 632586240, 790352640, 883396800, 900694080, 924168960, 1009800000, 1064448000
Offset: 1

Views

Author

Giovanni Resta, May 05 2006

Keywords

Comments

An Euler brick is a cuboid with integer sides and integer face diagonals.

Examples

			1235520 is the volume of the Euler brick with sides 240, 117 and 44, whose face diagonals are 267, 244 and 125.
		

Crossrefs

Extensions

Terms beyond a(21) from Peter T. C. Radden, Jan 12 2013
Showing 1-10 of 19 results. Next