A343080 a(n) is the smallest number that is the sum of n positive squares in three ways.

325, 54, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90

Offset

2,1

Comments

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

Links

Table of n, a(n) for n=2..66.

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 6, page 191.

Index entries for linear recurrences with constant coefficients, signature (2,-1).

Formula

a(n) = n + 24 for n >= 4.

Example

a(2) = 325 = 1^2 + 18^2 = 6^2 + 17^2 = 10^2 + 15^2.
a(3) = 54 = 1^2 + 2^2 + 7^2 = 2^2 + 5^2 + 5^2 = 3^2 + 3^2 + 6^2.

Crossrefs

Cf. A342902, A343083, A343081, A343082, A343083, A343084.

Sequence in context: A013763 A013887 A172198 * A159976 A253433 A253440

Adjacent sequences: A343077 A343078 A343079 * A343081 A343082 A343083

Keyword

nonn

Author

Sean A. Irvine, Apr 04 2021

Status

approved