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A261229
a(n) = number of steps to reach (n^3)-1 when starting from k = ((n+1)^3)-1 and repeatedly applying the map that replaces k with k - A055401(k), where A055401(k) = the number of positive cubes needed to sum to k using the greedy algorithm.
9
1, 3, 6, 9, 14, 19, 25, 31, 38, 44, 54, 62, 71, 81, 91, 103, 115, 129, 142, 157, 172, 187, 203, 221, 238, 256, 274, 294, 313, 335, 357, 378, 400, 424, 449, 473, 499, 525, 552, 579, 609, 637, 666, 698, 729, 760, 792, 827, 860, 895, 929, 967, 1002, 1039, 1077, 1117, 1155, 1195, 1235, 1278, 1318, 1361, 1404, 1448, 1492, 1538, 1583, 1631, 1677, 1725
OFFSET
1,2
LINKS
FORMULA
a(n) = A261226(((n+1)^3)-1) - A261226((n^3)-1). [The definition.]
Equally, for all n >= 1:
a(n) = A261226((n+1)^3) - A261226(n^3).
a(n) = A261227(n+1) - A261227(n).
a(n) = A261228(n+1) - A261228(n).
PROG
(Scheme, three variants, the first one utilizing memoization-macro definec)
(definec (A261229 n) (let ((end (- (A000578 n) 1))) (let loop ((k (- (A000578 (+ 1 n)) 1)) (s 0)) (if (= k end) s (loop (A261225 k) (+ 1 s))))))
(define (A261229 n) (- (A261228 (+ 1 n)) (A261228 n)))
(define (A261229 n) (- (A261226 (A000578 (+ 1 n))) (A261226 (A000578 n))))
CROSSREFS
First differences of both A261227 and A261228.
Cf. also A261224.
Sequence in context: A134031 A228172 A130473 * A184015 A225282 A242771
KEYWORD
nonn
AUTHOR
Antti Karttunen, Aug 16 2015
STATUS
approved