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Search: id:A106526
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| A106526 |
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Values of b in a^2-49=2*b^2. |
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+0
1
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| 4, 6, 14, 30, 40, 84, 176, 234, 490, 1026, 1364, 2856, 5980, 7950, 16646, 34854, 46336, 97020, 203144, 270066, 565474, 1184010, 1574060, 3295824, 6900916, 9174294, 19209470, 40221486, 53471704, 111960996, 234428000, 311655930, 652556506
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OFFSET
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1,1
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FORMULA
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a(1)=4, a(2)=6, a(3)=14, a(4)=30, a(5)=40 a(3n)=A001109(n)*14 a(3n+1)=A001109(n+2)-A001109(n+1)+A001109(n)+A001109(n-1) a(3n+2)=A001109(n+2)+A001109(n+1)-A001109(n)+A001109(n-1)
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EXAMPLE
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a(12)=2856; as mod(12,3)=0, a(12)=A001109(12/3)*14=204*14=2856; also 2*2856^2=4039^2-49, ie A106525(12)^2-49
a(13)=5980; as mod(13,3)=1, a(13)=A001109(4+2)-A001109(4+1)+A001109(4)+A001109(4-1)=6930-1189+204+35=5980; also 2*5980^2=8457^2-49, ie A106525(13)^2-49
a(14)=7950; as mod(14,3)=2, a(14)=A001109(4+2)+A001109(4+1)-A001109(4)+A001109(4-1)=6930+1189-204+35=7950; also 2*7950^2=11243^2-49, ie A106525(14)^2-49
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CROSSREFS
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Cf. A001109, A106525.
Adjacent sequences: A106523 A106524 A106525 this_sequence A106527 A106528 A106529
Sequence in context: A009849 A103419 A005202 this_sequence A108516 A077068 A096003
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KEYWORD
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nonn
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AUTHOR
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Andras Erszegi (erszegi.andras(AT)chello.hu), May 07 2005
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