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A025468
a(n) is the number of partitions of n into 2 distinct positive cubes.
7
0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
OFFSET
0,1730
COMMENTS
In other words, number of solutions to the equation n = x^3 + y^3 with x > y > 0. The first value > 1 is a(1729) = 2. - Antti Karttunen, Aug 29 2017
FORMULA
From Antti Karttunen, Aug 28-29 2017: (Start)
a(n) = A025465(n) - A025469(n).
a(n) <= A025455(n).
(End)
PROG
(Scheme) (define (A025468 n) (let loop ((x (A048766 n)) (s 0)) (let* ((x3 (A000578 x)) (y3 (- n x3))) (if (<= x3 y3) s (loop (- x 1) (+ s (if (and (> y3 0) (= (A000578 (A048766 y3)) y3)) 1 0))))))) ;; Antti Karttunen, Aug 28 2017
CROSSREFS
KEYWORD
nonn
STATUS
approved