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Search: id:A121383
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| A121383 |
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a(0)=3. a(n) = number of earlier terms which, each added to n, sum to a square. |
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+0
1
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| 3, 1, 0, 0, 0, 0, 1, 0, 2, 5, 0, 1, 0, 1, 1, 5, 7, 0, 1, 0, 2, 0, 1, 2, 7, 10, 1, 0, 0, 2, 0, 2, 0, 0, 2, 0, 1, 6, 8, 16
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Does every nonnegative integer occur eventually? Analogous to A123396 a(0)=0. a(n) = number of earlier terms each of which, when added to n, the sum is a triangular number.
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EXAMPLE
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a(6) = 1 because a(0) + 6 = 3 + 6 = 9 = 3^2.
a(20) = 2 because a(9) + 20 = a(15) + 20 = 25 = 5^2.
a(26) = 1 because a(25) + 26 = 10 + 26 = 36 = 6^2.
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CROSSREFS
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Cf. A123396.
Sequence in context: A087345 A140334 A078529 this_sequence A059530 A049828 A058612
Adjacent sequences: A121380 A121381 A121382 this_sequence A121384 A121385 A121386
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Oct 14 2006
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