A133282 -id:A133282 - cp's OEIS frontend

A108251 Numbers n such that googol - n is prime.

797, 911, 1287, 2127, 2217, 2247, 2303, 2457, 2841, 3221, 3407, 3531, 3921, 4353, 4361, 4403, 5097, 5459, 5867, 6173, 6261, 6531, 6741, 6939, 7133, 7271, 7311, 7707, 7797, 8651, 8841, 8951, 9347, 9401, 9599, 9669, 9729, 10001, 10773, 10937, 11663

Offset: 1

Cino Hilliard, Jun 17 2005

This sequence is finite with between 4.361969*10^97 and 4.361998*10^97 terms. Under the Riemann Hypothesis, it has 4.361971987140703159099509113229164611538757211...*10^97 terms. - Charles R Greathouse IV, Nov 23 2009

10^100-a(148) and 10^100-a(149) are the last twin primes less than 10^100. - T. D. Noe, Nov 03 2008

			A googol = 10^100. 10^100 - 797 is prime, so 797 is in the sequence.

T. D. Noe, Table of n, a(n) for n = 1..1000
For each of the 1000 terms in the table, 10^100 - a(n) was verified by the Magma Calculator as prime. - _Jon E. Schoenfield_, Aug 24 2009

Cf. A049014, A133282.

Rest[10^100-#&/@NestList[NextPrime[#,-1]&,10^100,50]] (* Harvey P. Dale, Jan 23 2017 *)

forstep(x=1,n,2,if(isprime(10^100-x),print1(x",")))

Edited by Charles R Greathouse IV, Nov 23 2009

A133281 Numbers k such that k + googol is a lower twin prime.

Original entry on oeis.org

35737, 58291, 59257, 63361, 87079, 138277, 141979, 175831, 178897, 219979, 365491, 394681, 413497, 503209, 558187, 599197, 655051, 730321, 747751, 757189, 763369, 788617, 831079, 861331, 865417, 870247, 900199, 947881, 1038217, 1081801, 1131037, 1165201, 1182229

Offset: 1

Cino Hilliard, Oct 13 2007

nonn

For k > 219979, k + a googol is a probable prime.

For each of the 28 terms listed, the Magma Calculator (http://magma.maths.usyd.edu.au/calc/) verified that both 10^100 + a(n) and 10^100 + a(n) + 2 were prime. - Jon E. Schoenfield, Aug 24 2009

Amiram Eldar, Table of n, a(n) for n = 1..1000

Cf. A001097, A001359, A006512, A133282.

Select[Range[10^6],And @@ PrimeQ[10^100 + # + {0, 2}] &] (* Amiram Eldar, Dec 26 2019 *)

googol(n) = { local(x,a,j); x=10^100; forstep(j=1,1000000,2, a=x+j; if(ispseudoprime(a)&ispseudoprime(a+2), print1(j","); ); ) }

Googol = 10^100.

More terms from Amiram Eldar, Dec 26 2019

cp's OEIS Frontend

A108251 Numbers n such that googol - n is prime.

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