A094942
Numbers having a unique partition into three squares.
Original entry on oeis.org
0, 1, 2, 3, 4, 5, 6, 8, 10, 11, 12, 13, 14, 16, 19, 20, 21, 22, 24, 30, 32, 35, 37, 40, 42, 43, 44, 46, 48, 52, 56, 58, 64, 67, 70, 76, 78, 80, 84, 88, 91, 93, 96, 115, 120, 128, 133, 140, 142, 148, 160, 163, 168, 172, 176, 184, 190, 192, 208, 224, 232, 235
Offset: 1
From _Wolfdieter Lang_, Apr 09 2013 (Start)
a(1) = 0 because 0 = 0^2 + 0^2 + 0^2 and 0 is the first number m with A000164(m)=1.
a(8) = 8 = 0^2 + 2^2 + 2^2, the 8th largest number m for which A000164(m) is 1.
(End)
Cf.
A025321 (numbers having a unique partition into three positive squares),
A094739 (primitive n having a unique partition into three squares).
A224442
Numbers that are the sum of three squares (square 0 allowed) in exactly two ways.
Original entry on oeis.org
9, 17, 18, 25, 26, 27, 29, 33, 34, 36, 38, 45, 49, 51, 53, 57, 59, 61, 62, 68, 69, 72, 73, 75, 77, 82, 83, 85, 94, 97, 100, 102, 104, 105, 106, 107, 108, 109, 116, 118, 123, 130, 132, 136, 138, 139, 141, 144, 147, 152, 154, 155, 157, 158, 165, 177, 180, 187
Offset: 1
a(1) = 9 = 0^2 + 0^2 + 3^2 = 1^2 + 2^2 + 2^2, and 9 is the smallest number m with A000164(m) = 2 for m >= 0. The multiplicity with order and signs taken into account is 2*3 + 8*3 = 30 = A005875(9).
The two representations [a,b,c] for a(n), n = 1, ..., 10, are
n=1, 9 = [0, 0, 3], [1, 2, 2],
n=2, 17 = [0, 1, 4], [2, 2, 3],
n=3, 18 = [0, 3, 3], [1, 1, 4],
n=4, 25 = [0, 0, 5], [0, 3, 4],
n=5, 26 = [0, 1, 5], [1, 3, 4],
n=6, 27 = [1, 1, 5], [3, 3, 3],
n=7, 29 = [0, 2, 5], [2, 3, 4],
n=8, 33 = [1, 4, 4], [2, 2, 5],
n=9, 34 = [0, 3, 5], [3, 3, 4],
n=10, 36 = [0, 0, 6], [2, 4, 4].
-
b:= proc(n, i, t) option remember; `if`(n=0, 1, `if`(t*i^22, 3, min(3, b(n, i-1, t)+
`if`(i^2>n, 0, b(n-i^2, i, t-1))))))
end:
a:= proc(n) option remember; local k;
for k from 1 +`if`(n=1, 0, a(n-1))
while b(k, isqrt(k), 3)<>2 do od; k
end:
seq(a(n), n=1..100); # Alois P. Heinz, Apr 09 2013
-
Select[ Range[0, 200], Length[ PowersRepresentations[#, 3, 2]] == 2 &] (* Jean-François Alcover, Apr 09 2013 *)
A294577
Numbers that are the sum of three squares (square 0 allowed) in exactly four ways.
Original entry on oeis.org
81, 89, 101, 125, 129, 134, 149, 161, 162, 170, 171, 173, 189, 198, 201, 233, 241, 242, 243, 245, 246, 249, 250, 251, 254, 270, 274, 278, 285, 289, 294, 299, 324, 339, 349, 356, 361, 363, 370, 371, 378, 387, 390, 393, 395, 404, 406, 411, 417, 429, 433, 451
Offset: 1
-
Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 4 &]
Updated Mathematica program to Version 11. by
Robert Price, Nov 01 2019
A294594
Numbers that are the sum of three squares (square 0 allowed) in exactly five ways.
Original entry on oeis.org
146, 153, 185, 206, 221, 225, 230, 234, 257, 261, 266, 293, 305, 325, 338, 350, 353, 354, 362, 377, 381, 398, 402, 405, 409, 410, 413, 414, 419, 437, 470, 474, 477, 481, 491, 514, 525, 539, 557, 563, 579, 582, 584, 586, 590, 611, 612, 625, 630, 635, 638, 642
Offset: 1
-
Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 5 &]
Updated Mathematica program to Version 11. by
Robert Price, Nov 01 2019
A294595
Numbers that are the sum of three squares (square 0 allowed) in exactly six ways.
Original entry on oeis.org
194, 209, 269, 281, 290, 297, 321, 326, 329, 342, 365, 386, 389, 401, 426, 434, 449, 459, 482, 485, 489, 497, 513, 531, 534, 542, 546, 554, 558, 561, 578, 601, 602, 633, 649, 659, 662, 665, 675, 678, 681, 693, 699, 705, 713, 714, 722, 737, 741, 747, 750, 754
Offset: 1
-
Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 6 &]
Updated Mathematica program to Version 11. by
Robert Price, Nov 01 2019
A294710
Numbers that are the sum of three squares (square 0 allowed) in exactly seven ways.
Original entry on oeis.org
306, 314, 341, 441, 450, 458, 494, 506, 581, 585, 593, 605, 654, 657, 674, 698, 706, 726, 731, 738, 746, 773, 806, 842, 850, 873, 890, 891, 893, 894, 899, 901, 905, 906, 934, 978, 985, 998, 1011, 1013, 1019, 1050, 1058, 1061, 1067, 1073, 1086, 1094, 1101
Offset: 1
-
Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 7 &]
Updated Mathematica program to Version 11. by
Robert Price, Nov 01 2019
A294711
Numbers that are the sum of three squares (square 0 allowed) in exactly eight ways.
Original entry on oeis.org
369, 374, 446, 461, 486, 509, 530, 549, 566, 621, 641, 666, 677, 686, 710, 749, 770, 789, 797, 818, 821, 825, 833, 849, 869, 882, 902, 945, 954, 962, 969, 971, 981, 1010, 1014, 1017, 1022, 1029, 1069, 1085, 1098, 1146, 1157, 1174, 1221, 1233, 1242, 1245
Offset: 1
-
Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 8 &]
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
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
Cf.
A000164,
A005875,
A000378,
A094942,
A224442,
A224443,
A294577,
A294594,
A294595,
A294710,
A294711.
-
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
-
Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 9 &]
Updated Mathematica program to Version 11. by
Robert Price, Nov 01 2019
A085625
Numbers that are the sum of 2 squares in exactly 2 ways.
Original entry on oeis.org
25, 50, 65, 85, 100, 125, 130, 145, 169, 170, 185, 200, 205, 221, 225, 250, 260, 265, 289, 290, 305, 338, 340, 365, 370, 377, 400, 410, 442, 445, 450, 481, 485, 493, 500, 505, 520, 530, 533, 545, 565, 578, 580, 585, 610, 629, 676, 680, 685, 689, 697, 730
Offset: 1
a(3) = 65 because 65 = 8^2 + 1^2 = 7^2 + 4^2;
a(4) = 85 because 85 = 9^2 + 2^2 = 7^2 + 6^2.
- David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See p. 125.
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Select[Range[730], Length[PowersRepresentations[#,2,2]]==2 &] (* Stefano Spezia, Sep 07 2024 *)
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
Cf.
A000164,
A005875,
A000378,
A094942,
A224442,
A224443,
A294577,
A294594,
A294595,
A294710,
A294711,
A294712.
-
Select[Range[0, 1000], Length[PowersRepresentations[#, 3, 2]] == 10 &]
Updated Mathematica program to Version 11. by
Robert Price, Nov 01 2019
Showing 1-10 of 10 results.
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