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Search: id:A067728
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| A067728 |
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Numbers such that 8 (8 + n) is a perfect square. |
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+0
9
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| 10, 24, 42, 64, 90, 120, 154, 192, 234, 280, 330, 384, 442, 504, 570, 640, 714, 792, 874, 960, 1050, 1144, 1242, 1344, 1450, 1560, 1674, 1792, 1914, 2040, 2170, 2304, 2442, 2584, 2730, 2880, 3034, 3192, 3354, 3520, 3690, 3864, 4042, 4224, 4410, 4600
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n+1)= 2*n*n +12*n +10 (frank.ellermann(AT)t-online.de).
a(n)=sum(sum(j-k, j=4..n),k=0..n):, n>=4 . - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 11 2007
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MAPLE
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a:=n->sum(sum(j-k, j=4..n), k=0..n): seq(a(n), n=4..49); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 11 2007
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MATHEMATICA
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Select[ Range[10000], IntegerQ[ Sqrt[ 8(8 + # )]] & ]
s=0; lst={}; Do[s+=n+1; s+=n+2; s+=n+3; s+=n+4; AppendTo[lst, s], {n, 0, 6!, 1}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 30 2008]
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CROSSREFS
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Cf. 7: A067727, 6: A067726, 5: A067724, 3: A067725.
Sequence in context: A101156 A162817 A103573 this_sequence A058504 A126911 A135285
Adjacent sequences: A067725 A067726 A067727 this_sequence A067729 A067730 A067731
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 05 2002
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