A352224 -id:A352224 - cp's OEIS frontend

A352133 Centered cube numbers that can be written as sums of two other cubes in at least one way.

91, 189, 1729, 12691, 68705, 97309, 201159, 400491, 2484755, 2554741, 3587409, 3767491, 8741691, 15407765, 26122131, 54814509, 121861441, 139361059, 168632191, 223264809, 236019771, 295233841, 355957875, 448404255, 508476241, 525518721, 1041378589, 2593625571, 2746367559, 2874318841, 4328420941, 5193550999

Offset: 1

Vladimir Pletser, Mar 05 2022

nonn

Numbers that are the sum of two consecutive cubes and at least one other sum of two cubes: a(n) = b(n)^3 + (b(n) + 1)^3 = c(n)^3 + d(n)^3, with c(n) > b(n) and c(n) > |d(n)|, and where b(n)=A352134(n), c(n)=A352135(n) and d(n)=A352136(n).

Subsequence of A005898.

			91 belongs to the sequence because 91 = 3^3 + 4^3 = 6^3 + (-5)^3.

Vladimir Pletser, Table of n, a(n) for n = 1..275
A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352134, A352135, A352136, A352220, A352221, A352222, A352223, A352224, A352225.

a(n) = A352134(n)^3 + (A352134(n) + 1)^3 = A352135(n)^3 + A352136(n)^3.

A352134 Numbers k such that the centered cube number k^3 + (k+1)^3 is equal to at least one other sum of two cubes.

Original entry on oeis.org

3, 4, 9, 18, 32, 36, 46, 58, 107, 108, 121, 123, 163, 197, 235, 301, 393, 411, 438, 481, 490, 528, 562, 607, 633, 640, 804, 1090, 1111, 1128, 1293, 1374, 1436, 1517, 1524, 1538, 1543, 1698, 2018, 2047, 2361, 3032, 3152, 3280, 3321, 4131, 4995, 5092, 5659, 5687, 5700

Offset: 1

Vladimir Pletser, Mar 05 2022

nonn

The centered cube number a(n)^3 + (a(n) + 1)^3 is equal to at least one other sum of two cubes: a(n)^3 + (a(n) + 1)^3 = b(n)^3 + c(n)^3 = d(n), with b(n) > a(n) and b(n) > |c(n)|, and where b(n)=A352135(n), c(n)=A352136(n) and d(n)=A352133(n).

A number k is a term iff t = k^3 + (k+1)^3 = (2*k + 1)*(k^2 + k + 1) has one or more divisors s < 2*k such that 12*t/s - 3*s^2 is a square. Each such divisor s is the sum of two integers (other than k and k+1) whose cubes sum to t. - Jon E. Schoenfield, Mar 09 2022

			3 belongs to the sequence as 3^3 + 4^3 = 6^3 + (-5)^3 = 91.
From _Jon E. Schoenfield_, Mar 11 2022: (Start)
The table below lists the first 15 pairs of integers (b,c) such that b > c+1 and b^3 + c^3 is a centered cube number k^3 + (k+1)^3 = d.
Note that there are two pairs (b,c) for k=121 and two for k=163. For these and for all numbers k for which there is more than one pair (b,c), the pair with the smallest value of b is chosen as the one whose values (b,c) appear in A352135 and A352136, i.e., A352135(n) and A352136(n) are the values (b,c) in that pair whose value of b is smallest.
Thus, the 15 solutions listed in the table account for only the first 13 terms of this sequence and of A352133, A352135, and A352136.
.
   n  a(n)=k     d(n)  b(n)  c(n)
  --  ------  -------  ----  ----
   1       3       91     6    -5
   2       4      189     6    -3
   3       9     1729    12     1
   4      18    12691    28   -21
   5      32    68705    41    -6
   6      36    97309    46    -3
   7      46   201159   151  -148
   8      58   400491    90   -69
   9     107  2484755   171  -136
  10     108  2554741   181  -150
  11     121  3587409   153    18  (153 < 369)
   *     121  3587409   369  -360  ((b,c) omitted from A352135,A352136)
  12     123  3767491   160   -69
  13     163  8741691   206    -5  (206 < 254)
   *     163  8741691   254  -197  ((b,c) omitted from A352135,A352136)
(End)

Chai Wah Wu, Table of n, a(n) for n = 1..917 (terms 1..275 from Vladimir Pletser)
A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352135, A352136, A352220, A352221, A352222, A352223, A352224, A352225.

a:=[]; for k in [1..5700] do t:=k^3+(k+1)^3; for s in Divisors(t) do if s gt 2*k then break; end if; if IsSquare(12*(t div s) - 3*s^2) then a[#a+1]:=k; break; end if; end for; end for; a; // Jon E. Schoenfield, Mar 09 2022

a(n)^3 + (a(n) + 1)^3 = A352135(n)^3 + A352136(n)^3 = A352133(n).

Missing terms inserted by Jon E. Schoenfield, Mar 09 2022

A352135 Numbers j in pairs (j,k), with j <> k +- 1, such that the sum of their cubes is equal to a centered cube number.

Original entry on oeis.org

6, 6, 12, 28, 41, 46, 151, 90, 171, 181, 153, 160, 206, 1016, 292, 378, 513, 531, 831, 633, 618, 3753, 710, 1119, 1410, 830, 1246, 1307, 1623, 1506, 1629, 1752, 1845, 1917, 1917, 2019, 10815, 2140, 22331, 2871, 3660, 4481, 3881, 4230, 43356, 9955, 6294, 76621, 22988, 7170, 21253

Offset: 1

Vladimir Pletser, Mar 05 2022

nonn

Numbers j such that j^3 + k^3 = m^3 + (m + 1)^3 = N, with j <> (k +- 1), j > m and j > |k|, and where j = a(n) (this sequence), k = A352136(n), m = A352134(n) and N = A352133(n).
In case there are two or more pairs of numbers (j, k) such that the sum of their cubes equals the same centered cube number, the smallest occurrence of j is shown in the sequence. For other occurrences, see A352224(n) and A352225(n).
Terms in Data are ordered according to increasing order of A352133(n) or A352134(n).

			6 belongs to the sequence as 6^3 + (-5)^3 = 3^3 + 4^3 = 91.

Vladimir Pletser, Table of n, a(n) for n = 1..258
A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352134, A352136, A352220, A352221, A352222, A352223, A352224, A352225.

a(n)^3 + A352136(n)^3 = A352134(n)^3 + (A352134(n) + 1)^3 = A352133(n).

Missing terms inserted by Jon E. Schoenfield, Mar 11 2022

A352136 Numbers k in pairs (j,k), with j <> k +- 1, such that the sum of their cubes is equal to a centered cube number.

Original entry on oeis.org

-5, -3, 1, -21, -6, -3, -148, -69, -136, -150, 18, -69, -5, -1011, 107, 93, -236, -218, -740, -312, -21, -3746, -125, -984, -1319, -359, -963, 712, -1152, -815, 178, -569, -706, -382, 346, -982, -10794, -69, -22320, -1866, -2831, -3246, 1614, -1719, -43343, -9456, -197, -76606, -22757, -865, -20976

Offset: 1

Vladimir Pletser, Mar 05 2022

sign

Numbers k such that j^3 +k^3 = m^3 + (m + 1)^3 = N, with j <> (k +- 1), j > m and j > |k|, and where j = A352135(n), k = a(n) (this sequence), m = A352134(n) and N = A352133(n).
In case there are two or more pairs of numbers (j, k) such that the sum of their cubes equals the same centered cube number, the smallest occurrence of j is shown in the sequence. For other occurrences, see A352224(n) and A352225(n).
Terms in Data are ordered according to increasing order of A352133(n) or A352134(n).

			-5 belongs to the sequence as 6^3 + (-5)^3 = 3^3 + 4^3 = 91.

Vladimir Pletser, Table of n, a(n) for n = 1..258
A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352134, A352135, A352220, A352221, A352222, A352223, A352224, A352225.

A352135(n)^3 + a(n)^3 = A352134(n)^3 + (A352134(n) + 1)^3 = A352133(n).

A352223 Second members D of two non-consecutive numbers such that the sums of their cubes are equal to centered cube numbers and to at least one other sum of two cubes, i.e., A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3.

Original entry on oeis.org

18, -5, 107, -125, 712, -1152, -1719, -865, -5370, -7870, 2518, -963, -29949, -20030, 111491, 87797, 261536, 2274319, -140357, -3938794, -139674130, -792131385

Offset: 1

Vladimir Pletser, Mar 07 2022

Numbers D such that A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3 with C <> (D +- 1), E <> (F +- 1), E > C > B, C > |D| and E > |F|, where A = A352220(n), B = A352221(n), C = A352222(n), D = a(n) (this sequence), E = A352224(n) and F = A352225(n).
Terms in Data are ordered according to increasing order of A352220(n) or A352221(n).
Subsequence of A352136.

			18 belongs to the sequence as 153^3 + 18^3 = 121^3 + 122^3 = 369^3 + (-360)^3 = 3587409.

A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352134, A352135, A352136, A352220, A352221, A352222, A352224, A352225.

A352223(n)^3 + a(n)^3 = A352221(n)^3 + (A352221(n) + 1)^3 = A352224(n)^3 + A352225(n)^3 = A352220(n).

a(21) from Chai Wah Wu, Mar 17 2022

a(22) from Bert Dobbelaere, Apr 18 2022

A352225 Second numbers F = a(n) of two non-consecutive numbers (E, F) different from (C, D) = (A352222(n), A352223(n)), such that the sums of their cubes are equal to centered cube numbers and to at least one other sum of two cubes, i.e. A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3.

Original entry on oeis.org

-360, -197, -362, -2805, -3866, -10081, -29511, -5905, -227790, -10012, -24548, -28995, -875133, -73040, -615709, -457027, -3044074, -17549681, -4232837, -4999714, -13724102460, -94822721073

Offset: 1

Vladimir Pletser, Mar 07 2022

Numbers F such that A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3 with C <> (D +- 1), E <> (F +- 1), E > C > B, C > |D| and E > |F|, where A = A352220(n), B = A352221(n), C = A352222(n), D = A352223(n), E = A352224(n) and F = a(n) (this sequence).

Terms are ordered according to increasing order of A352220(n) or A352221(n).

			-360 belongs to the sequence as 369^3 + (-360)^3 = 121^3 + 122^3 = 153^3 + 18^3 = 3587409.

A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352134, A352135, A352136, A352220, A352221, A352222, A352223, A352224.

A352224(n)^3 + a(n)^3 = A352221(n)^3 + (A352221(n) + 1)^3 = A352222(n)^3 + A352223(n)^3 = A352220(n).

a(21) from Chai Wah Wu, Mar 17 2022

a(22) from Bert Dobbelaere, Apr 18 2022

A352220 Centered cube numbers that can be written as sums of two other cubes in at least two ways.

Original entry on oeis.org

3587409, 8741691, 26122131, 355957875, 2593625571, 2746367559, 70607389041, 367954598375, 7006302268875, 7916366521691, 8091803325879, 28332679374909, 144757538551899, 1026401875608375, 9339629571431315, 14295468330521189, 49873257556492139, 42892025638971003759

Offset: 1

Vladimir Pletser, Mar 07 2022

nonn

Numbers A such that A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3 with C <> (D +- 1), E <> (F +- 1), E > C > B, C > |D| and E > |F|, where A = a(n) (this sequence), B = A352221(n), C = A352222(n), D = A352223(n), E = A352224(n) and F = A352225(n).

Subsequence of A005898 and of A352133.

			3587409 belongs to the sequence because 3587409 = 121^3 + 122^3 = 153^3 + 18^3 = 369^3 + (-360)^3.

A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352134, A352135, A352136, A352221, A352222, A352223, A352224, A352225.

a(n) = A352221(n)^3 + (A352221(n) + 1)^3 = A352222(n)^3 + A352223(n)^3 = A352224(n)^3 + A352225(n)^3.

a(6)-a(18) from Jon E. Schoenfield, Mar 09 2022

A352221 Numbers k such that the centered cube number k^3 + (k+1)^3 is equal to at least two other sums of two cubes.

Original entry on oeis.org

121, 163, 235, 562, 1090, 1111, 3280, 5687, 15187, 15818, 15934, 24196, 41674, 80062, 167147, 192629, 292154, 2778319, 3532195, 7906844, 58400437, 248878534

Offset: 1

Vladimir Pletser, Mar 07 2022

Numbers B such that the centered cube number B^3 + (B+1)^3 is equal to at least two other sums of two cubes, i.e., A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3 with C <> (D +- 1), E <> (F +- 1), E > C > B, C > |D| and E > |F|, where A = A352220(n), B = a(n) (this sequence), C = A352222(n), D = A352223(n), E = A352224(n) and F = A352225(n).

Subsequence of A352134.

			121 is a term because 121^3 + 122^3 = 153^3 + 18^3 = 369^3 + (-360)^3 = 3587409.

A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352134, A352135, A352136, A352220, A352222, A352223, A352224, A352225.

a(n)^3 + (a(n)+1)^3 = A352222(n)^3 + A352223(n)^3 = A352224(n)^3 + A352225(n)^3 = A352220(n).

a(6)-a(20) from Jon E. Schoenfield, Mar 10 2022
a(21) from Chai Wah Wu, Mar 17 2022
a(22) from Bert Dobbelaere, Apr 18 2022

A352222 First members C of two non-consecutive numbers such that the sums of their cubes are equal to centered cube numbers and to at least one other sum of two cubes, i.e., A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3.

Original entry on oeis.org

153, 206, 292, 710, 1307, 1623, 4230, 7170, 19275, 20331, 20063, 30486, 55572, 101135, 199614, 238806, 317427, 3145700, 4450334, 10163157, 146173525, 808182534

Offset: 1

Vladimir Pletser, Mar 07 2022

Numbers C such that A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3 with C <> (D +- 1), E <> (F +- 1), E > C > B, C > |D| and E > |F|, where A = A352220(n), B = A352221(n), C = a(n) (this sequence), D = A352223(n), E = A352224(n) and F = A352225(n).
Terms are ordered according to increasing order of A352220(n) or A352221(n).
Subsequence of A352135.

			153 belongs to the sequence as 153^3 + 18^3 = 121^3 + 122^3 = 369^3 + (-360)^3 = 3587409.

A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Eric Weisstein's World of Mathematics, Centered Cube Number

Cf. A005898, A001235, A272885, A352133, A352134, A352135, A352136, A352220, A352221, A352223, A352224, A352225.

a(n)^3 + A352223(n)^3 = A352221(n)^3 + (A352221(n) + 1)^3 = A352224(n)^3 + A352225(n)^3 = A352220(n).

a(21) from Chai Wah Wu, Mar 17 2022

a(22) from Bert Dobbelaere, Apr 18 2022

A352755 Positive centered cube numbers that can be written as the difference of two positive cubes: a(n) = t(3t^2 + 4)(t^2(3t^2 + 4)^2 + 3)/4 with t = 2n-1 and n > 0.

Original entry on oeis.org

91, 201159, 15407765, 295233841, 2746367559, 16448122691, 73287987409, 264133278045, 811598515091, 2202365761759, 5410166901741, 12249942682409, 25914353312575, 51755729480091, 98389720844009, 179211321358741, 314429627203659, 533744613620855, 879807401606341, 1412624924155809

Offset: 1

Vladimir Pletser, Apr 02 2022

Numbers A > 0 such that A = B^3 + (B+1)^3 = C^3 - D^3 and such that C - D = 2n - 1, with C > D > B > 0, and A = t*(3*t^2 + 4)*(t^2*(3*t^2 + 4)^2 + 3)/4 with t = 2*n-1, and where A = a(n) (this sequence), B = A352756(n), C = A352757(n) and D = A352758(n).
There are infinitely many such numbers a(n) = A in this sequence.
Subsequence of A005898, of A352133 and of A352220.

			a(1) = 91 belongs to the sequence because 91 = 3^3 + 4^3 = 6^3 - 5^3 and 6 - 5 = 1 = 2*1 - 1.
a(2) = 201159 belongs to the sequence because 201159 = 46^3 + 47^3 = 151^3 - 148^3 and 151 - 148 = 3 = 2*2 - 1.
a(3) = (2*3 - 1)*(3*(2*3 - 1)^2 + 4)*((2*3 - 1)^2*(3*(2*3 - 1)^2 + 4)^2 + 3)/4 = 15407765.

Vladimir Pletser, Table of n, a(n) for n = 1..10000
A. Grinstein, Ramanujan and 1729, University of Melbourne Dept. of Math and Statistics Newsletter: Issue 3, 1998.
Vladimir Pletser, Euler's and the Taxi-Cab relations and other numbers that can be written twice as sums of two cubed integers, submitted. Preprint available on ResearchGate, 2022.
Eric Weisstein's World of Mathematics, Centered Cube Number
Index entries for linear recurrences with constant coefficients, signature (10,-45,120,-210,252,-210,120,-45,10,-1).

Cf. A005898, A001235, A272885, A352133, A352134, A352135, A352136, A352221, A352222, A352223, A352224, A352225, A352756, A352757, A352758, A352759, A355751, A355752, A355753.

restart; for n to 20 do (1/4)*(2*n-1)*(3*(2*n-1)^2+4)*((2*n-1)^2*(3*(2*n-1)^2+4)^2+3) end do;

a(n) = A352756(n)^3 + (A352756(n) + 1)^3 = A352757(n)^3 - A352758(n)^3 and A352757(n) - A352758(n) = 2n - 1.
a(n) = (2*n - 1)*(3*(2*n - 1)^2 + 4)*((2*n - 1)^2*(3*(2*n - 1)^2 + 4)^2 + 3)/4.
a(n) can be extended for negative n such that a(-n) = -a(n+1).

cp's OEIS Frontend

A352133 Centered cube numbers that can be written as sums of two other cubes in at least one way.

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A352134 Numbers k such that the centered cube number k^3 + (k+1)^3 is equal to at least one other sum of two cubes.

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A352135 Numbers j in pairs (j,k), with j <> k +- 1, such that the sum of their cubes is equal to a centered cube number.

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A352136 Numbers k in pairs (j,k), with j <> k +- 1, such that the sum of their cubes is equal to a centered cube number.

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A352223 Second members D of two non-consecutive numbers such that the sums of their cubes are equal to centered cube numbers and to at least one other sum of two cubes, i.e., A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3.

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A352225 Second numbers F = a(n) of two non-consecutive numbers (E, F) different from (C, D) = (A352222(n), A352223(n)), such that the sums of their cubes are equal to centered cube numbers and to at least one other sum of two cubes, i.e. A = B^3 + (B+1)^3 = C^3 + D^3 = E^3 + F^3.

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A352220 Centered cube numbers that can be written as sums of two other cubes in at least two ways.

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A352221 Numbers k such that the centered cube number k^3 + (k+1)^3 is equal to at least two other sums of two cubes.

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A352755 Positive centered cube numbers that can be written as the difference of two positive cubes: a(n) = t(3t^2 + 4)(t^2(3t^2 + 4)^2 + 3)/4 with t = 2n-1 and n > 0.