A343079 -id:A343079 - cp's OEIS frontend

A342902 a(n) is the smallest number that is the sum of n positive cubes in two ways.

1729, 251, 219, 157, 158, 131, 132, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126

Offset: 2

N. J. A. Sloane, Apr 03 2021

nonn

This is r(n,3,2) in Alter's notation.

			a(2) = 1729 = 12^3 + 1^3 = 10^3 + 9^3 (the famous Hardy-Ramanujan number).
a(3) = 251 = 5^3 + 5^3 + 1^3 = 6^3 + 3^3 + 2^3.

R. Alter, Computations and generalizations on a remark of Ramanujan, pp. 182-196 of "Analytic Number Theory (Philadelphia, 1980)", ed. M. I. Knopp, Lect. Notes Math., Vol. 899, 1981. See Table 2, page 190.
Index entries for linear recurrences with constant coefficients, signature (2,-1).

Cf. A001235, A011541, A230563, A342903, A343077, A343078, A343079, A343081, A343085.

a(n) = n+63 for n >= 9.

A343077 a(n) is the smallest number that is the sum of n positive 4th powers in two ways.

Original entry on oeis.org

635318657, 2673, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292

Offset: 2

Sean A. Irvine, Apr 04 2021

nonn

This is r(n,4,2) in Alter's notation.

			a(2) = 635318657 = 59^4 + 158^4 = 133^4 + 134^4.
a(3) = 2673 = 2^4 + 4^4 + 7^4 = 3^4 + 6^4 + 6^4.

R. Alter, Computations and generalizations on a remark of Ramanujan, pp. 182-196 of "Analytic Number Theory (Philadelphia, 1980)", ed. M. I. Knopp, Lect. Notes Math., Vol. 899, 1981. See Table 3, page 190.
Index entries for linear recurrences with constant coefficients, signature (2,-1).

Cf. A003824, A046881, A342902, A343078, A343079, A343082, A343086.

a(n) = n + 240 for n >= 16.

A343078 a(n) is the smallest number that is the sum of n positive 5th powers in two ways.

Original entry on oeis.org

1375298099, 51445, 4097, 4098, 4099, 4100, 4101, 4102, 4103, 4104, 4105, 4106, 4107, 4108, 4109, 4110, 4111, 4112, 4113, 4114, 4115, 4116, 4117, 4118, 4119, 4120, 4121, 4122, 4123, 4124, 1056, 1057, 1058, 1059, 1060, 1061, 1062, 1063, 1064, 1065, 1066, 1067

Offset: 3

Sean A. Irvine, Apr 04 2021

nonn

This is r(n,5,2) in Alter's notation.

			a(3) = 1375298099 = 3^5 + 54^5 + 62^5 = 24^5 + 28^5 + 67^5.
a(4) = 51445 = 4^5 + 7^5 + 7^5 + 7^5 = 5^5 + 6^5 + 6^5 + 8^5.

R. Alter, Computations and generalizations on a remark of Ramanujan, pp. 182-196 of "Analytic Number Theory (Philadelphia, 1980)", ed. M. I. Knopp, Lect. Notes Math., Vol. 899, 1981. See Table 4, page 190.
Index entries for linear recurrences with constant coefficients, signature (2,-1).

Cf. A230563, A342902, A343077, A343079, A343083.

a(n) = n + 1023 for n >= 33.

cp's OEIS Frontend

A342902 a(n) is the smallest number that is the sum of n positive cubes in two ways.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Formula

A343077 a(n) is the smallest number that is the sum of n positive 4th powers in two ways.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Formula

A343078 a(n) is the smallest number that is the sum of n positive 5th powers in two ways.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Formula