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 A048927 Numbers that are the sum of 5 positive cubes in exactly 2 ways. 9
 157, 220, 227, 246, 253, 260, 267, 279, 283, 286, 305, 316, 323, 342, 344, 361, 368, 377, 379, 384, 403, 410, 435, 440, 442, 468, 475, 487, 494, 501, 523, 530, 531, 549, 562, 568, 586, 592, 594, 595, 599, 602, 621, 625, 640, 647, 657, 658, 683, 703, 710 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS It appears that this sequence has 15416 terms, the last of which is 2243453. - Donovan Johnson, Jan 11 2013 From a(1) = 157 we see that c(n) = (number of ways n is the sum of 5 cubes) coincides with A010057 = characteristic function of cubes, up to n = 156. This sequence lists the numbers n for which c(n) = 2. See A003328 for c(n) > 0 and A048926 for c(n) = 1. - M. F. Hasler, Jan 04 2023 LINKS Donovan Johnson, Table of n, a(n) for n = 1..15416 (terms < 10^8) Eric Weisstein's World of Mathematics, Cubic Number. MATHEMATICA Select[ Range[ 1000], (test = Length[ Select[ PowersRepresentations[#, 5, 3], And @@ (Positive /@ #)& ] ] == 2; If[test, Print[#]]; test)& ](* Jean-François Alcover, Nov 09 2012 *) PROG (Python) def ways (n, left = 5, last = 1): a = last; a3 = a**3; c = 0 while a3 <= n-left+1: if left > 1: c += ways(n-a3, left-1, a) elif a3 == n: c += 1 a += 1; a3 = a**3 return c for n in range (1, 1000): # to print this sequence if ways(n)==2: print(n, end=", ") # in Python2 use, e.g.: print n, # Minor edits by M. F. Hasler, Jan 04 2023 (PARI) (waycount(n, numcubes, imax)={if(numcubes==0, !n, sum(i=1, imax, waycount(n-i^3, numcubes-1, i)))}); isA048927(n)=(waycount(n, 5, floor(n^(1/3)))==2); \\ Michael B. Porter, Sep 27 2009 CROSSREFS Cf. A003328 (sums of 5 positive cubes), A025404, A048926 (sum of 5 positive cubes in exactly 1 way), A048930, A294736, A343702, A343705, A344237. Sequence in context: A140035 A007356 A236537 * A343702 A163490 A142063 Adjacent sequences: A048924 A048925 A048926 * A048928 A048929 A048930 KEYWORD nonn AUTHOR Eric W. Weisstein EXTENSIONS More terms from Walter Hofmann (walterh(AT)gmx.de), Jun 01 2000 STATUS approved

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Last modified June 17 15:57 EDT 2024. Contains 373463 sequences. (Running on oeis4.)