A265845 Numbers that are sums of consecutive (positive) cubes in more than one way.

216, 8000, 33075, 64000, 89559, 105525, 164800, 188784, 189189, 216000, 343000, 353241, 443456, 608391, 1271600, 2370816, 3132116, 3132675, 3184236, 5821200, 5832000, 9018000, 9769375, 11437525, 20793591, 22153600, 24359616, 28685440, 35937000, 47651373

Offset

1,1

Comments

A131643 (cubes that are also sums of three or more consecutive positive cubes) is a sparse subsequence: only 17 of its terms appear in the first 1000 terms of A265845. - Jonathan Sondow, Jan 10 2016

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Example

a(1) = 216 = 6^3 = 3^3 + 4^3 + 5^3;
a(2) = 8000 = 20^3 = 11^3 + 12^3 + 13^3 + 14^3;
a(3) = 33075 = 11^3 + 12^3 + 13^3 + 14^3 + 15^3 + 16^3 + 17^3 + 18^3 + 19^3 = 15^3 + 16^3 + 17^3 + 18^3 + 19^3 + 20^3.

Prog

(Haskell)
import Data.Set (singleton, deleteFindMin, insert, Set)
a265845 n = a265845_list !! (n-1)
a265845_list = f (singleton (1, (1, 1))) 0 0 where
   f s z z' = if y == z && z' /= z then y : f s'' y z else f s'' y z
              where s'' = (insert (y', (i, j')) $
                           insert (y' - i ^ 3 , (i + 1, j')) s')
                    y' = y + j' ^ 3; j' = j + 1
                    ((y, (i, j)), s') = deleteFindMin s

Crossrefs

Subsequence of A217843; subsequences: A000578, A005898, A027602, A027603, A062682.

Supersequence of A131643.

Sequence in context: A017595 A232835 A223272 * A131643 A269139 A231319

Adjacent sequences: A265842 A265843 A265844 * A265846 A265847 A265848

Keyword

nonn

Author

Reinhard Zumkeller, Dec 16 2015

Status

approved