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A128356
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Least number k>1 (that is not the power of prime p) such that k divides (p+1)^k-1, where p = Prime[n].
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9
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20, 21, 1555, 889, 253, 2041, 5846759, 148305659, 1081, 279241, 9641, 950123, 33661, 63213709997, 583223, 3775349, 72707647, 149070763, 196932497, 5091481, 25760459, 14307947980741, 13861, 9362711, 376457, 132766545553, 63757
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| All listed terms have 2 distinct prime divisors. Most listed terms are semiprimes, except a(7) = 20231*17^2 and a(8) = 410819*19^2. p = Prime[n] divides a(n). Quotients a(n)/Prime[n] are listed in A128357(n) = {10, 7, 311, 127, 23, 157, 343927, ...}. a(15) = 583223 = 47*12409. a(16) = 3775349 = 53*71233.
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CROSSREFS
| Cf. A014960, A128360, A128358, A014960, A014956, A014951, A014949, A014946, A014945, A067945. Cf. A128357 = Quotients A128356(n)/Prime[n].
Sequence in context: A041836 A041837 A041838 * A109212 A050653 A095453
Adjacent sequences: A128353 A128354 A128355 * A128357 A128358 A128359
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KEYWORD
| hard,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Mar 02 2007
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EXTENSIONS
| Terms a(14) onwards from Max Alekseyev (maxale(AT)gmail.com), Feb 08 2010
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