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Search: id:A117474
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| A117474 |
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The values of 'a' in a^2 + b^2 = c^2 where b - a = 7 and gcd(a,b,c)=1. |
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+0
2
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| 5, 8, 48, 65, 297, 396, 1748, 2325, 10205, 13568, 59496, 79097, 346785, 461028, 2021228, 2687085, 11780597, 15661496, 68662368, 91281905, 400193625, 532029948, 2332499396, 3100897797, 13594802765, 18073356848
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OFFSET
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1,1
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COMMENT
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The values of 'c' are in A060569
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FORMULA
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a(1)=5, a(2)=8, a(3)=48, a(4)=65, a(n) = 6*a(n-2) - a(n-4) + 14
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EXAMPLE
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a(5) = 6*48 - 5 + 14 = 297, and 297^2 + 304^2 = 425^2, and 304 -297 = 7 and gcd(297, 304, 425) = 1
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MAPLE
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g:=proc(n) option remember; if n=1 then RETURN(5) fi; if n=2 then RETURN(8) fi; if n=3 then RETURN(48) fi; if n=4 then RETURN(65) fi; 6*g(n-2)-g(n-4)+14; end; [njas, Oct 06 2007]
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CROSSREFS
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Cf. A060569.
Sequence in context: A130223 A126750 A109292 this_sequence A068478 A132050 A123819
Adjacent sequences: A117471 A117472 A117473 this_sequence A117475 A117476 A117477
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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), Mar 19 2006
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