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Search: id:A157579
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| A157579 |
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Half the number of length n integer sequences with sum zero and sum of squares 4418. |
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+0
1
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| 1, 3, 294, 21630, 1556655, 102426933, 6421722076, 420393758436, 26609856588945, 1503958534048245, 77827209776501394, 3793522397195559678, 177172760525971961023, 8001788984919141620040, 350900981113969220953080
(list; graph; listen)
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OFFSET
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2,2
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LINKS
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Ron Hardin, Table of n, a(n) for n=2..50
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FORMULA
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[cache enabling] count(n,s,ss)->count(n,t,tt) where t=s mod n, q=(t-s)/n, tt=ss+2*q*s+n*q^2; count(n,t,tt)=sum[i^2<=tt]{ count(n-1,t-i,tt-i^2) }. a(n)=count(n,0,4418)/2.
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CROSSREFS
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Sequence in context: A058455 A116532 A124357 this_sequence A104821 A119065 A119069
Adjacent sequences: A157576 A157577 A157578 this_sequence A157580 A157581 A157582
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KEYWORD
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nonn
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AUTHOR
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Ron Hardin (rhhardin(AT)att.net) Mar 02 2009
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