A228575
Pseudoprimes n to base 2 such that n-4, n-2 and n+2 are primes.
Original entry on oeis.org
645, 656601, 6212361, 18958567881, 287468425245, 626160901281, 1395494019921, 1925525109201, 1960708164801, 1962378065901, 1977370759365, 2788325761551, 3032013857181, 6877227801081, 22298617759881, 30242009317521, 39454593651201, 42401101442001
Offset: 1
645 is a pseudoprime (base 2) and 641, 643 and 647 are primes.
A230488
Pseudoprimes n to base 2 such that n-2 and n-4 are primes.
Original entry on oeis.org
645, 33153, 129921, 157641, 451905, 656601, 1608465, 3020361, 3370641, 6212361, 19092921, 34487601, 38790753, 681942801, 940492785, 1109260545, 1574300001, 2693081973, 3037396461, 4160578521, 6424683105, 7384487181, 13671360561, 14966031345, 15731001105
Offset: 1
645 is a pseudoprime (base 2) and 643 and 641 are primes.
A230489
Pseudoprimes n to base 2 such that n+2 and n+4 are primes.
Original entry on oeis.org
87249, 831405, 1489665, 2113665, 31880577, 81612105, 84028407, 86559045, 274014885, 1778357505, 1853263365, 2276082537, 9090685605, 12300409857, 43620860865, 69654751377, 248342283645, 634038307449, 848282877345, 1123296404385, 1344952805505, 3307428792777
Offset: 1
87249 is a pseudoprime (base 2) and 87251 and 87253 are primes.
A287591
Carmichael numbers k such that k-2 and k+2 are both primes.
Original entry on oeis.org
656601, 25536531021, 8829751133841, 60561233400921, 79934093254401, 352609909731201, 598438077923841, 976515437206401, 2122162714918401, 2789066007968241, 3767175573114801, 7881891474971361, 10740122274670881, 11512252145095521, 16924806963384321
Offset: 1
656601 is in the sequence since it is a Carmichael number (A002997) and both 656599 and 656603 are primes.
- Amiram Eldar, Table of n, a(n) for n = 1..282 (terms below 10^22, calculated using data from Claude Goutier)
- Claude Goutier, Compressed text file carm10e22.gz containing all the Carmichael numbers up to 10^22.
- R. G. E. Pinch, Tables relating to Carmichael numbers.
- Andrzej Rotkiewicz, On pseudoprimes having special forms and a solution of K. Szymiczek's problem, Acta Mathematica Universitatis Ostraviensis, Vol. 13, No. 1 (2005), pp. 57-71.
A230485
Strong pseudoprimes n to base 2 such that n-2 and n+2 are primes.
Original entry on oeis.org
3465253618401, 44202753561285411, 1640293473202755801, 10623546148468360251
Offset: 1
3465253618401 is a strong pseudoprime (base 2) and 3465253618399 and 3465253618403 are primes.
A230559
Pseudoprimes n to base 2 such that n-2, n+2 and n+4 are primes.
Original entry on oeis.org
634038307449, 4846359321105, 11927878640385, 20835183400305, 34166605315305, 54096163177785, 63154533545265, 88365393281985, 189080281720065, 850943773070385, 917252751841665, 1278728202166185, 1602254869802049, 3742704749436465, 6082185264252945
Offset: 1
634038307449 is a pseudoprime (base 2) and 634038307447, 634038307451 and 634038307453 are primes.
A228455
Pseudoprimes n to base 2 such that n-2, n+2, n-4 and n+4 are primes.
Original entry on oeis.org
280743771536011785, 666787209284980785, 1386744766793550165, 6558237049521329745, 11646802313400102465
Offset: 1
280743771536011785 is a pseudoprime (base 2) and 280743771536011781, 280743771536011783, 280743771536011787 and 280743771536011789 are primes.
A287297
Fermat pseudoprimes n such that n+1 is prime.
Original entry on oeis.org
161038, 9115426, 143742226, 665387746, 1105826338, 3434672242, 11675882626, 16732427362, 18411253246, 81473324626, 85898088046, 98730252226, 134744844466, 136767694402, 161097973246, 183689075122, 315554044786, 553588254766, 778581406786, 1077392692846
Offset: 1
161038 is in the sequence since it is a Fermat pseudoprime (2^161038 == 2 (mod 161038)), and 161038 + 1 = 161039 is prime.
- Andrzej Rotkiewicz, Pseudoprime Numbers and Their Generalizations, Student Association of the Faculty of Sciences, University of Novi Sad, Novi Sad, Yugoslavia, 1972.
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