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Search: id:A127072
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| A127072 |
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Numbers n such that n divides 3^n - 2^n - 1. |
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+0
9
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| 1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 27, 29, 31, 32, 37, 41, 43, 45, 47, 49, 53, 59, 61, 64, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Prime p divides 3^p - 2^p - 1. Quotients (3^p - 2^p - 1)/p, where p = Prime[n], are listed in A127071(n) = {2,6,42,294,15918,122010,7588770,61144062,4092816966,2366546223930,...}. Pseudoprimes in a(n) include all powers of primes {2,3,7} and some composite numbers that are listed in A127073(n) = {45,245,405,561,637,639,833,891,...}. Numbers n such that n^2 divides 3^n - 2^n - 1 are listed in A127074(n) = {1,2,3,4,7,49,179,619,...}. Numbers n such that n^3 divides 3^n - 2^n - 1 are {1,4,7,...}.
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MATHEMATICA
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Select[Range[1000], IntegerQ[(3^#-2^#-1)/# ]&]
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CROSSREFS
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Cf. A127071, A127073, A127074.
Sequence in context: A164336 A115919 A038701 this_sequence A056781 A079446 A115975
Adjacent sequences: A127069 A127070 A127071 this_sequence A127073 A127074 A127075
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KEYWORD
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nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Jan 04 2007
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