A383359 Integers m such that m^4 is the sum of squares of two or more consecutive positive integers.

13, 295, 330, 364, 1085, 5005, 6305, 15516, 415151, 1990368, 34011252, 42016497, 79565281, 139107722, 254801664, 418093065, 667378972, 1214995500, 3609736702, 4353556896

Offset

1,1

Comments

a(21) > 10^10. - Xianwen Wang, May 08 2025

Terms of A383653 such that the consecutive integers are all positive.

From David A. Corneth, May 04 2025: (Start)

The sum of the first m positive squares is f(m) = m*(m + 1)*(2*m + 1) / 6.

The sum of consecutive squares m^2 + (m+1)^2 + ... + t^2 where 0 < m <= t may be written as f(t) - f(m-1) for some t and m.

From there we can factor out t - m - 1 and solve the system of equations going over divisors of 6*m^4.

To get divisors of 6*m^4 we need to factor 6*m^4 which can be done using the factors of 6 and the factors of m. Doing so makes we need to factorize smaller numbers. (End)

Links

Table of n, a(n) for n=1..20.

Zhining Yang, Can be expressed as the fourth power of the sum of squares of consecutive positive integers, Chinese BBS.

Example

295 is a term because 295^4 = 6453^2 + 6454^2 + ... + 6628^2 + 6629^2.

Mathematica

d[m_] := Select[Divisors[6 m^4], 1 < # < Floor@ CubeRoot[3 m^4] &&
    IntegerQ[1/6 (-3 (1 + #) + Sqrt[3 (12 m^4/# + 1 - #^2)])] &];
Do[If[Length@d[m] > 0, Print[m]], {m, 1, 10000}]

Crossrefs

Cf. A000330, A097812, A189173, A383367, A383653.

Sequence in context: A023357 A165218 A317632 * A076130 A035272 A296319

Adjacent sequences: A383356 A383357 A383358 * A383360 A383361 A383362

Keyword

nonn,more

Author

Zhining Yang, May 01 2025

Extensions

a(11)-a(18) from Xianwen Wang, May 04 2025

a(19)-a(20) from Xianwen Wang, May 08 2025

Status

approved