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A067063 Smallest prime factor of repunit(n) = (10^n-1)/9 (A002275). 9
11, 3, 11, 41, 3, 239, 11, 3, 11, 21649, 3, 53, 11, 3, 11, 2071723, 3, 1111111111111111111, 11, 3, 11, 11111111111111111111111, 3, 41, 11, 3, 11, 3191, 3, 2791, 11, 3, 11, 41, 3, 2028119, 11, 3, 11, 83, 3, 173, 11, 3, 11, 35121409, 3, 239 (list; graph; refs; listen; history; internal format)
OFFSET

2,1

COMMENTS

a(3n) = 3, a(6n-4) = a(6n-2) = 11, a(30n-25) = a(30n-5) = 41, ... - M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 21 2006

REFERENCES

Amarnath Murthy, On the divisors of Smarandache Unary Sequence, Smarandache Notions Journal, Vol. 11, No. 1-2-3, Spring 2000.

David Wells, The Penguin Dictionary of Curious and Interesting Numbers.

LINKS

T. D. Noe, Table of n, a(n) for n=2..500 (derived from Yousuke Koide)

M. L. Perez et al., eds., Smarandache Notions Journal

Samuel S. Wagstaff, the Cunningham Project

Makoto Kamada, Factorizations of 11...11 (Repunit).

Yousuke Koide, Factorizations of Repunit Numbers

MAPLE

'min(op(numtheory[factorset]((10^k-1)/9)))'$k=2..50; - M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 21 2006

MATHEMATICA

a = {}; Do[a = Append[a, FactorInteger[(10^n - 1)/9][[1, 1]]], {n, 2, 111} ]; a

CROSSREFS

Cf. A003020, A002275, A102380.

Sequence in context: A194706 A110435 A110774 * A075023 A205960 A088262

Adjacent sequences:  A067060 A067061 A067062 * A067064 A067065 A067066

KEYWORD

nonn

AUTHOR

Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jan 03 2002

EXTENSIONS

More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 04 2002

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Last modified February 12 07:22 EST 2012. Contains 205378 sequences.