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Search: id:A132215
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| A132215 |
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Numbers that are sums of eighth powers of two distinct primes. |
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+0
5
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| 6817, 390881, 397186, 5765057, 5771362, 6155426, 214359137, 214365442, 214749506, 220123682, 815730977, 815737282, 816121346, 821495522, 1030089602, 6975757697, 6975764002, 6976148066, 6981522242, 7190116322, 7791488162
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OFFSET
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1,1
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COMMENT
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This is to 8th powers as A132214 is to 7th powers, A130555 is to 6th powers, A130292 is to fifth powers, A130873 is to 4th powers, and A120398 is to cubes. These CAN be prime, as the polynomial x^8 + y^8 is irreducible over Z, as seen in A132216. The first such example is a(11) = A132216(1) = 2^8 + 13^8 = 256 + 815730721 = 815730977, which is prime.
A subset of A003380. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 11 2008
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FORMULA
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{A001016(A000040(i)) + A001016(A000040(j)) for i > j}.
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EXAMPLE
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a(1) = 2^8 + 3^8 = 256 + 6561 = 6817 = 17 * 401.
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MATHEMATICA
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Select[Sort[ Flatten[Table[Prime[n]^8 + Prime[k]^8, {n, 15}, {k, n - 1}]]], # <= Prime[15^8] &]
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CROSSREFS
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Cf. A000040, A001016, A050997, A120398, A122616, A130873, A130555, A132214, A132216.
Sequence in context: A031832 A121106 A046515 this_sequence A075669 A066878 A114772
Adjacent sequences: A132212 A132213 A132214 this_sequence A132216 A132217 A132218
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Aug 13 2007
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