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A084741 Smallest prime of the form (n^k+1)/(n+1), or 0 if no such prime exists. 19
3, 7, 13, 521, 31, 43, 0, 73, 9091, 13421, 19141, 157, 7027567, 211, 241, 22796593, 307, 274019342889240109297, 152381, 421, 463, 39700406579747, 183458857, 601, 135938684703251, 0, 757, 574995877 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
When n is a power (greater than 2) of a prime, then (n^k+1)/(n+1) will usually be composite for all k, which is the case for n = 8, 27, 32, 64, 125. The next term, a(30), is a 204-digit number. - T. D. Noe, Jan 22 2004
LINKS
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
EXAMPLE
a(7)= 43 = (7^3 +1 )/(7+1) = 1 - 7 + 7^2 is a prime.
CROSSREFS
Cf. A084742 (least k such that (n^k+1)/(n+1) is prime).
Sequence in context: A322301 A154821 A353008 * A135623 A172291 A343589
KEYWORD
nonn
AUTHOR
Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 15 2003
EXTENSIONS
More terms from T. D. Noe, Jan 22 2004
STATUS
approved

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Last modified March 18 21:02 EDT 2024. Contains 370951 sequences. (Running on oeis4.)