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.

Previous Showing 11-18 of 18 results.

A294578 Numbers which can be expressed as an ordered sum of 3 squares in 6 or more different ways.

Original entry on oeis.org

194, 209, 269, 281, 290, 297, 306, 314, 321, 326, 329, 341, 342, 365, 369, 374, 386, 389, 401, 425, 426, 434, 441, 446, 449, 450, 458, 459, 461, 482, 485, 486, 489, 494, 497, 506, 509, 513, 521, 530, 531, 534, 542, 545, 546, 549, 554, 558, 561, 566, 569, 578
Offset: 1

Views

Author

Robert Price, Nov 02 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[578], Length[PowersRepresentations[#, 3, 2]] >= 6 &]

Extensions

Updated Mathematica program to Version 11. by Robert Price, Nov 01 2019

A294712 Numbers that are the sum of three squares (square 0 allowed) in exactly nine ways.

Original entry on oeis.org

425, 521, 545, 569, 614, 650, 701, 725, 729, 774, 809, 810, 845, 857, 953, 974, 989, 990, 1053, 1062, 1070, 1074, 1091, 1118, 1134, 1139, 1166, 1179, 1217, 1249, 1251, 1262, 1266, 1277, 1298, 1310, 1418, 1446, 1458, 1470, 1525, 1541, 1546, 1571, 1594, 1611
Offset: 1

Views

Author

Robert Price, Nov 07 2017

Keywords

Comments

These are the numbers for which A000164(a(n)) = 9.
a(n) is the n-th largest number which has a representation as a sum of three integer squares (square 0 allowed), in exactly nine ways, if neither the order of terms nor the signs of the numbers to be squared are taken into account. The multiplicity of a(n) with order and signs taken into account is A005875(a(n)).
This sequence is a proper subsequence of A000378.

Examples

			545 =  8^2 + 15^2 + 16^2
    =  0^2 + 16^2 + 17^2
    = 10^2 + 11^2 + 18^2
    =  5^2 + 14^2 + 18^2
    =  8^2 +  9^2 + 20^2
    =  1^2 + 12^2 + 20^2
    =  2^2 + 10^2 + 21^2
    =  5^2 +  6^2 + 22^2
    =  0^2 +  4^2 + 23^2. - _Robert Israel_, Nov 08 2017
		

Crossrefs

Programs

  • Maple
    N:= 10000: # to get all terms <= N
    V:= Array(0..N):
    for i from 0 to isqrt(N) do
      for j from 0 to i while i^2 + j^2 <= N do
        for k from 0 to j while i^2 + j^2 + k^2 <= N do
          t:= i^2 + j^2 + k^2;
          V[t]:= V[t]+1;
    od od od:
    select(t -> V[t] = 9, [$1..N]); # Robert Israel, Nov 08 2017
  • Mathematica
    Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 9 &]

Extensions

Updated Mathematica program to Version 11. by Robert Price, Nov 01 2019

A294596 Numbers which can be expressed as an ordered sum of 3 squares in 7 or more different ways.

Original entry on oeis.org

306, 314, 341, 369, 374, 425, 441, 446, 450, 458, 461, 486, 494, 506, 509, 521, 530, 545, 549, 566, 569, 581, 585, 593, 594, 605, 614, 621, 626, 629, 641, 650, 654, 657, 666, 674, 677, 686, 689, 698, 701, 706, 710, 725, 726, 729, 731, 734, 738, 746, 749, 761
Offset: 1

Views

Author

Robert Price, Nov 03 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[761], Length[PowersRepresentations[#, 3, 2]] >= 7 &]

Extensions

Updated Mathematica program to Version 11. by Robert Price, Nov 01 2019

A294597 Numbers which can be expressed as an ordered sum of 3 squares in 8 or more different ways.

Original entry on oeis.org

369, 374, 425, 446, 461, 486, 509, 521, 530, 545, 549, 566, 569, 594, 614, 621, 626, 629, 641, 650, 666, 677, 686, 689, 701, 710, 725, 729, 734, 749, 761, 770, 774, 789, 794, 797, 801, 809, 810, 818, 821, 825, 833, 845, 846, 849, 854, 857, 866, 869, 881, 882
Offset: 1

Views

Author

Robert Price, Nov 03 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[1000],Length[PowersRepresentations[#,3,2]]>7&] (* Harvey P. Dale, Jul 03 2019 *)

A294713 Numbers that are the sum of three squares (square 0 allowed) in exactly ten ways.

Original entry on oeis.org

594, 626, 629, 734, 846, 914, 926, 929, 1001, 1026, 1041, 1097, 1125, 1190, 1193, 1209, 1214, 1229, 1241, 1265, 1289, 1326, 1329, 1382, 1386, 1409, 1433, 1490, 1505, 1509, 1521, 1530, 1581, 1637, 1689, 1691, 1713, 1725, 1730, 1739, 1749, 1754, 1770, 1778
Offset: 1

Views

Author

Robert Price, Nov 07 2017

Keywords

Comments

These are the numbers for which A000164(a(n)) = 10.
a(n) is the n-th largest number which has a representation as a sum of three integer squares (square 0 allowed), in exactly ten ways, if neither the order of terms nor the signs of the numbers to be squared are taken into account. The multiplicity of a(n) with order and signs taken into account is A005875(a(n)).
This sequence is a proper subsequence of A000378.

Crossrefs

Programs

  • Mathematica
    Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 10 &]

Extensions

Updated Mathematica program to Version 11. by Robert Price, Nov 01 2019

A294714 Numbers which can be expressed as an ordered sum of 3 squares in 9 or more different ways.

Original entry on oeis.org

425, 521, 545, 569, 594, 614, 626, 629, 650, 689, 701, 725, 729, 734, 761, 774, 794, 801, 809, 810, 845, 846, 854, 857, 866, 881, 909, 914, 926, 929, 941, 950, 953, 965, 974, 986, 989, 990, 1001, 1025, 1026, 1034, 1041, 1046, 1049, 1053, 1062, 1070, 1074
Offset: 1

Views

Author

Robert Price, Nov 07 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[882], Length[PowersRepresentations[#, 3, 2]] >= 9 &]

Extensions

Updated Mathematica program to Version 11. by Robert Price, Nov 01 2019

A287164 Primes having a unique partition into three squares.

Original entry on oeis.org

2, 3, 5, 11, 13, 19, 37, 43, 67, 163
Offset: 1

Views

Author

Ilya Gutkovskiy, May 20 2017

Keywords

Comments

D. H. Lehmer conjectures that there are no more terms (see A094739 and A094942).

Examples

			-------------------------------
|  n | a(n) | representation  |
|-----------------------------|
|  1 |   2  | 0^2 + 1^2 + 1^2 |
|  2 |   3  | 1^2 + 1^2 + 1^2 |
|  3 |   5  | 0^2 + 1^2 + 2^2 |
|  4 |  11  | 1^2 + 1^2 + 3^2 |
|  5 |  13  | 0^2 + 2^2 + 3^2 |
|  6 |  19  | 1^2 + 3^2 + 3^2 |
|  7 |  37  | 0^2 + 1^2 + 6^2 |
|  8 |  43  | 3^2 + 3^2 + 5^2 |
|  9 |  67  | 3^2 + 3^2 + 7^2 |
| 10 | 163  | 1^2 + 9^2 + 9^2 |
-------------------------------
157 is the prime of the form x^2 + y^2 + z^2 with x, y, z >= 0, but is not in the sequence because 157 = 0^2 + 6^2 + 11^2 = 2^2 + 3^2 + 12^2.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[200], Length[PowersRepresentations[#, 3, 2]] == 1 && PrimeQ[#] &]

A294715 Numbers which can be expressed as an ordered sum of 3 squares in 10 or more different ways.

Original entry on oeis.org

594, 626, 629, 689, 734, 761, 794, 801, 846, 854, 866, 881, 909, 914, 926, 929, 941, 950, 965, 986, 1001, 1025, 1026, 1034, 1041, 1046, 1049, 1089, 1097, 1106, 1109, 1121, 1125, 1130, 1154, 1161, 1169, 1181, 1190, 1193, 1205, 1206, 1209, 1214, 1226, 1229
Offset: 1

Views

Author

Robert Price, Nov 07 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[1229], Length[PowersRepresentations[#, 3, 2]] >= 10 &]

Extensions

Updated Mathematica program to Version 11, and corrected errors in Name. by Robert Price, Nov 01 2019
Previous Showing 11-18 of 18 results.