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A106488 Numbers n such that 1_666.2_666.3_666 ... 8_666.9_666.10^n+1 is prime, i.e. 1 repeated 666 times, concatenated with 2 repeated 666 times etc. 1
641, 1788, 1918, 3731, 7093, 8009 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

These are "subscript" primes, similar to those listed in Table 30 of the Primal Configurations document. Only 3731, 7093 and 8009 have been proved prime. The others are Fermat and Lucas PRPs. Primality proof for the largest (14003 digits): PFGW Version 20041001.Win_Stable (v1.2 RC1b) [FFT v23.8] Primality testing (r(666,1)*10^5328+r(666,2)*10^4662+r(666,3)*10^3996+r(666,4)*10^3330+r(666,5)*10^2664+r(666,6)*10^1998+r(666,7)*10^1332+r(666,8)*10^666+r(666,9))*10^8009+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 17 (r(666,1)*10^5328+r(666,2)*10^4662+r(666,3)*10^3996+r(666,4)*10^3330+r(666,5)*10^2664+r(666,6)*10^1998+r(666,7)*10^1332+r(666,8)*10^666+r(666,9))*10^8009+1 is prime! (38.8002s+0.0106s)

LINKS

R. Ondrejka, The Top Ten: a Catalogue of Primal Configurations.

CROSSREFS

Sequence in context: A160203 A105130 A117129 * A206164 A206378 A135384

Adjacent sequences:  A106485 A106486 A106487 * A106489 A106490 A106491

KEYWORD

base,nonn

AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), May 29 2005

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Last modified February 17 04:58 EST 2012. Contains 205985 sequences.