A120735 Least positive k such that saw(n) + k is prime, where saw(n) = (1111120*(-1+10^(10*n))/900009).

21, 27, 97, 21, 151, 163, 243, 79, 313, 159, 933, 197, 257, 483, 313, 1049, 337, 353, 33, 217, 751, 257, 1777, 193, 81, 343, 647, 3, 393, 737, 381, 553, 709, 471, 543, 1237, 23, 699, 419, 1251, 843, 953, 497, 1303, 557, 1803, 841, 397, 273, 681, 319, 263, 231

Offset

1,1

Comments

The majority of the decimal expansions of these (probable) primes rise and fall to form a "sawtooth" pattern, e.g. a(3)=97 and saw(3)+97 = 1234565432123456543212345654417. a(1000)=5291. Proof: PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing (1111120*(-1+10^(10000))/900009)+5291 [N-1/N+1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 2 Running N-1 test using base 3 Running N+1 test using discriminant 11, base 2+sqrt(11) (1111120*(-1+10^(10000))/900009)+5291 is Fermat and Lucas PRP!

Links

Table of n, a(n) for n=1..53.

Crossrefs

Sequence in context: A208157 A114168 A103083 * A009727 A337702 A168105

Adjacent sequences: A120732 A120733 A120734 * A120736 A120737 A120738

Keyword

nonn

Author

Jason Earls, Aug 18 2006

Status

approved