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Search: id:A120929
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| 1, 2, 18, 19701, 4294986997, 298023228171940122, 10314424798788558774343889178
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OFFSET
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0,2
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COMMENT
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After 2, can this ever be prime? This is to A001923 Sum k^k, k=1..n, as k^k^k is to k^k.
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FORMULA
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a(n) = sum[i=0..n] i^i^i. a(n) = sum[i=0..n] i^(i^2). a(n) = sum[i=0..n] (i^i)^i. In this sequence, we formally define 0^0 = 1.
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EXAMPLE
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a(0) = 1 because A002489(0) is given formally as 0^0^0 = 1.
a(1) = 2 because 1 + 1^1^1 = 1 + 1 = 2.
a(2) = 18 because 2 + 2^2^2 = 2 + 16 = 18.
a(3) = 19701 because 18 + 3^3^3 = 18 + 19683 = 19701.
a(4) = 4294986997 = 19701 + 4^4^4 = 19701 + 4294967296.
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CROSSREFS
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Cf. A001923, A002489, A002488, A001329, A002488, A023813, A076113, A090588.
Sequence in context: A003043 A059783 A066361 this_sequence A007184 A067765 A086367
Adjacent sequences: A120926 A120927 A120928 this_sequence A120930 A120931 A120932
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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 18 2006
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