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A061496
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a(n) = gcd(abundant(n), abundant(n+1)) where abundant(n) is the n-th abundant number.
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1
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6, 2, 4, 6, 6, 4, 2, 6, 6, 2, 4, 6, 2, 2, 6, 2, 4, 4, 2, 6, 4, 2, 2, 4, 4, 2, 6, 6, 6, 6, 2, 4, 6, 6, 4, 2, 6, 6, 2, 4, 6, 6, 4, 2, 2, 4, 4, 2, 6, 4, 2, 2, 4, 6, 6, 6, 6, 6, 2, 4, 6, 2, 4, 4, 2, 6, 6, 6, 4, 2, 2, 4, 6, 2, 4, 6, 6, 4, 2, 6, 2, 2, 2, 6, 4, 2, 2
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OFFSET
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1,1
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COMMENTS
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The first occurrence of 1, 2, 3, 4, 5 and 6 is at n = 1432, 2, 231, 3, 1335014838 and 1, respectively. There are no terms larger than 6. - Amiram Eldar, Feb 22 2023
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LINKS
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FORMULA
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EXAMPLE
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a(1) = gcd(12, 18) = 6.
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MATHEMATICA
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GCD @@@ Partition[Select[Range[400], DivisorSigma[-1, #] > 2 &], 2, 1] (* Amiram Eldar, Feb 22 2023 *)
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PROG
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(PARI) { x=12; for (n=1, 1000, y=x+1; until (sigma(y) > 2*y, y++); write("b061496.txt", n, " ", gcd(x, y)); x=y ) } \\ Harry J. Smith, Jul 23 2009
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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