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Search: id:A094523
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| A094523 |
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Numbers n not of the form i^2+(i+1)^2 such that there are integers a < b with a^2+(a+1)^2+...+(n-1)^2 = n^2+(n+1)^2+...+b^2. |
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+0
2
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| 35, 39, 51, 111, 143, 160, 856, 2251, 2471, 2611, 3031, 3840, 3893, 4291, 5223, 5385, 5730, 7490, 7828, 9488, 21576, 27650, 30396, 31683, 38936, 41580, 48793, 56871, 60456, 64240, 64805, 66115, 85485, 90013
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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When n=i^2+(i+1)^2, then a=n-i-1 and b=n+i-1 is a solution. See A094553.
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EXAMPLE
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35 is in this sequence because 18^2+19^2+...+34^2 = 35^2+36^2+...+42^2 and 35 is not the sum of two consecutive squares.
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MATHEMATICA
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lst={}; Do[i1=n-1; i2=n; s1=i1^2; s2=i2^2; While[i1>1 && s1!=s2, If[s1<s2, i1--; s1=s1+i1^2, i2++; s2=s2+i2^2]]; m=(i2-i1)/2; m=m^2+(m+1)^2; If[s1==s2 && n!=m, AppendTo[lst, n]], {n, 2, 100000}]; lst
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CROSSREFS
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Cf. A001844 (sum of two consecutive squares), A094553.
Sequence in context: A030589 A114965 A061755 this_sequence A141741 A122755 A033857
Adjacent sequences: A094520 A094521 A094522 this_sequence A094524 A094525 A094526
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), May 10 2004
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