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A157542
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Half the number of length n integer sequences with sum zero and sum of squares 200.
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1
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1, 3, 42, 930, 17685, 265041, 3668483, 44840097, 529728300, 5955342987, 65311345275, 699155920398, 7170690213960, 69964606094670, 652763403442422, 5868431782886486, 51137730082075059, 433379839761592641
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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LINKS
| R. H. Hardin, Table of n, a(n) for n=2..50
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FORMULA
| [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,0,200)/2.
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CROSSREFS
| Sequence in context: A097068 A092470 A206820 * A078601 A195010 A156108
Adjacent sequences: A157539 A157540 A157541 * A157543 A157544 A157545
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KEYWORD
| nonn
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net) Mar 02 2009
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