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Search: id:A157563
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| A157563 |
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Half the number of length n integer sequences with sum zero and sum of squares 1922. |
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+0
1
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| 1, 9, 198, 9930, 447345, 19373781, 801643164, 34613610228, 1445069106945, 53870000270295, 1838679236576886, 59112727361906010, 1820954720583759943, 54244177130219463765, 1568969312068377795960, 44074283494841644862536
(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,0,1922)/2.
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CROSSREFS
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Sequence in context: A017426 A110807 A019566 this_sequence A003026 A157594 A064756
Adjacent sequences: A157560 A157561 A157562 this_sequence A157564 A157565 A157566
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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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