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Search: id:A048927
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| A048927 |
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Numbers that are the sum of 5 positive cubes in exactly 2 ways. |
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+0
2
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| 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; listen)
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OFFSET
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1,1
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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PROGRAM
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(Python: replace leading dots by blanks):
.def ways (n, left=5, last=1):
.. a=last; a3=a*a*a; c=0
.. while a3<=n-left+1:
.... if left>1:
...... c=c+ways(n-a3, left-1, a)
.... elif a3==n:
...... c=c+1
.... a=a+1; a3=a*a*a
.. return c
.for n in range (1, 1000):
.. c=ways(n)
.. if c==2:
.... print n,
(PARI) waycount(n, numcubes, imax)={if(numcubes==0, if(n==0, 1, 0), sum(i=1, imax, waycount(n-i^3, numcubes-1, i)))}; isA048927(n)=(waycount(n, 5, floor(n^(1/3)))==2); [From Michael Porter (michael_b_porter(AT)yahoo.com), Sep 27 2009]
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CROSSREFS
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Cf. A003328, A048926.
Sequence in context: A096704 A140035 A007356 this_sequence A142063 A151739 A142231
Adjacent sequences: A048924 A048925 A048926 this_sequence A048928 A048929 A048930
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KEYWORD
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nonn
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AUTHOR
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Eric Weisstein (eric(AT)weisstein.com)
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EXTENSIONS
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More terms from Walter Hofmann (walterh(AT)gmx.de), Jun 01 2000
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