**About 27121 Prime Search**

PrimeGrid and 12121 Search are now collaborating in an effort to find a Mega Prime of the form 121*2^n-1. This is very similar to the 321 Prime Search at k=3.

12121 Search was established on 5/24/2004 to search for large primes of the form 121*2^n-1. Later, they added k=27 to their search. Their "short term" goal is to search for n up to 10M. For more information, please visit their site: **12121 Search**.

As we did with 321, we are going to test the +1 form of these k's in parallel as well. Therefore, the effort will consist of the following:

121*2^n+1, 121*2^n-1

27*2^n+1, 27*2^n-1

for n<10M

## Known PrimesEdit

Primes known for 27*2^n-1 occur at the following n:

1, 2, 4, 5, 8, 10, 14, 28, 37, 38, 70, 121, 122, 160, 170, 253, 329, 362, 454, 485, 500, 574, 892, 962, 1213, 1580, 2642, 2708, 4505, 8152, 11858, 13300, 15041, 16118, 16778, 19069, 22769, 29020, 30298, 30377, 35942, 42817, 42869, 62024, 74629, 90449, 91042, 117901, 128594, 143330, 152530, 157898, 175852, 282700, 340682, 444622, 627794, 729314, 777992, 1108214, 1163629, 1253870, 1902689, 3855094

Primes known for 27*2^n+1 occur at the following n:

2, 4, 7, 16, 19, 20, 22, 26, 40, 44, 46, 47, 50, 56, 59, 64, 92, 175, 215, 275, 407, 455, 1076, 1090, 3080, 3322, 6419, 7639, 19360, 30500, 38770, 44164, 50696, 114760, 117784, 153847, 160874, 178739, 379880, 405514, 672007, 974752, 1164664, 1476347, 2218064

Primes known for 121*2^n-1 occur at the following n:

1, 3, 21, 27, 37, 43, 91, 117, 141, 163, 373, 421, 1581, 2035, 10701, 18931, 21307, 51195, 64579, 156541, 302097, 334257, 368059, 383061, 410131, 494317, 541621, 990219, 1039965, 1526097, 1589157, 1695499, 1954243, 2033941, 4553899

Primes known for 121*2^n+1 occur at the following n:

8, 12, 44, 84, 96, 228, 264, 320, 732, 788, 1808, 7928, 12264, 37784, 59196, 91112, 112208, 168716, 251184, 264632, 272052, 513020, 636564, 674360