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A076980
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Leyland numbers: numbers expressible as n^k + k^n nontrivially, i.e. n,k > 1 (to avoid n = (n-1)^1 +1^(n-1)).
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8
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8, 17, 32, 54, 57, 100, 145, 177, 320, 368, 512, 593, 945, 1124, 1649, 2169, 2530, 4240, 5392, 6250, 7073, 8361, 16580, 18785, 20412, 23401, 32993, 60049, 65792, 69632, 93312, 94932, 131361, 178478, 262468, 268705, 397585, 423393, 524649, 533169
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OFFSET
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1,1
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COMMENTS
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Crandall & Pomerance named these numbers in honor of Paul Leyland, in reference to 2638^4405 + 4405^2638, the largest known prime of this form. - Alonso del Arte, Apr 05 2006
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REFERENCES
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R. Crandall and C. Pomerance, Prime Numbers: A Computational Perspective, Springer, NY, 2005
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
Wikipedia, Leyland number.
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EXAMPLE
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a(7) = 177 because we can write 177 = 2^7 + 7^2
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MATHEMATICA
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Take[Sort[Flatten[Table[x^y + y^x, {x, 2, 100}, {y, x, 100}]]], 42] - Alonso del Arte, Apr 05 2006
nn=10^50; n=1; Union[Reap[While[n++; num=2*n^n; num<nn, Sow[num]; k=n; While[k++; num=n^k+k^n; num<nn, Sow[num]]]][[2, 1]]]
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CROSSREFS
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Prime subset of this sequence, A094133.
Sequence in context: A077222 A077221 A106648 * A209376 A159696 A049713
Adjacent sequences: A076977 A076978 A076979 * A076981 A076982 A076983
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 23 2002
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EXTENSIONS
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More terms from Benoit Cloitre, Oct 24 2002
More terms from Alonso del Arte, Apr 05 2006
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STATUS
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approved
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