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A265845
Numbers that are sums of consecutive (positive) cubes in more than one way.
7
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
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
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Dec 16 2015
STATUS
approved