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Search: id:A133664
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| A133664 |
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Primes of the form a^a + b^b + c^c + d^d. |
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+0
3
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| 7, 13, 59, 311, 337, 769, 3137, 3389, 9631, 46691, 49783, 49789, 139969, 143093, 823601, 826673, 826699, 870253, 916859, 16777729, 16780369, 16780601, 16823903, 16827001, 17600761, 17600813, 18427427, 33557561, 33604213, 34378231
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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A000040 INTERSECTION {A000312(a) + A000312(b) + A000312(c) + A000312(d)}.
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EXAMPLE
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a(1) = 7 = 2^2 + 1^1 + 1^1 + 1^1 = 4 + 1 + 1 + 1 = 7 is prime.
a(2) = 13 = 4 + 4 + 4 + 1.
a(3) = 59 = 27 + 27 + 4 + 1.
a(4) = 311 = 256 + 27 + 27 + 1.
a(5) = 337 = 256 + 27 + 27 + 27.
a(6) = 769 = 256 + 256 + 256 + 1.
a(7) = 3137 = 3125 + 4 + 4 + 4.
a(8) = 3389 = 3125 + 256 + 4 + 4.
a(9) = 9631 = 3125 + 3125 + 3125 + 256.
a(10) = 46691 = 46656 + 27 + 4 + 4.
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MATHEMATICA
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Select[Union[ Flatten[Table[ a^a + b^b + c^c + d^d, {a, 1, 20}, {b, 1, a}, {c, 1, b}, {d, 1, c}]]], PrimeQ]
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CROSSREFS
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Cf. A000040, A000312, A068145.
Sequence in context: A112540 A015441 A091005 this_sequence A143794 A106976 A098478
Adjacent sequences: A133661 A133662 A133663 this_sequence A133665 A133666 A133667
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Dec 28 2007
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