A228575 -id:A228575 - cp's OEIS frontend

A230559 Pseudoprimes n to base 2 such that n-2, n+2 and n+4 are primes.

634038307449, 4846359321105, 11927878640385, 20835183400305, 34166605315305, 54096163177785, 63154533545265, 88365393281985, 189080281720065, 850943773070385, 917252751841665, 1278728202166185, 1602254869802049, 3742704749436465, 6082185264252945

Offset: 1

Shyam Sunder Gupta, Oct 27 2013

nonn

All numbers in this sequence end in either 5 or 9.

			634038307449 is a pseudoprime (base 2) and 634038307447, 634038307451 and 634038307453 are primes.

Shyam Sunder Gupta, Table of n, a(n) for n = 1..82

Cf. A001567, A057942, A230488, A230489, A228575.

A230715 Smallest numbers in a set of 4 consecutive odd numbers that are primes or pseudoprime (base 2).

Original entry on oeis.org

641, 656597, 6212357, 18958567877, 287468425241, 626160901277, 634038307447, 1395494019917, 1925525109197, 1960708164797, 1962378065897, 1977370759361, 2788325761547, 3032013857177, 4846359321103, 6877227801077, 11927878640383, 20835183400303, 22298617759877

Offset: 1

Shyam Sunder Gupta, Oct 28 2013

nonn

			656597 is in sequence because 656597, 656599, 656601, 656603 is a set of 4 consecutive odd number where 656601 is pseudoprime base 2 and others are prime.

Shyam Sunder Gupta, Table of n, a(n) for n = 1..913
Jan Feitsma, Tables of pseudoprimes and related data

Cf. A001567, A230559, A228575, A230668.

\\ Import A001567 into the vector v
for(i=1,#v, start=stop=v[i]; while(ok(start-=2),); while(ok(stop+=2),); while(stop-start>9, print1(start+=2, ", "))) \\ Charles R Greathouse IV, Oct 28 2013

A230808 Smallest sets of 3 consecutive odd numbers that are primes or pseudoprime (base 2). The initial odd number is listed.

Original entry on oeis.org

3, 641, 643, 4369, 25759, 33149, 87249, 129917, 157637, 212419, 332947, 451901, 656597, 656599, 831405, 1489665, 1608461, 2113665, 3020357, 3370637, 6212357, 6212359, 19092917, 31880577, 34487597, 38790749, 63560683, 81612105, 84028407, 86559045, 274014885

Offset: 1

Shyam Sunder Gupta, Oct 30 2013

nonn

			641 is in sequence because 641, 643, 645 is a set of 3 consecutive odd number where 645 is pseudoprime base 2 and others are prime.

Shyam Sunder Gupta, Table of n, a(n) for n = 1..5001
Jan Feitsma, Tables of pseudoprimes and related data

Cf. A001567, A230559, A228575, A230668, A230715.

cp's OEIS Frontend

A230559 Pseudoprimes n to base 2 such that n-2, n+2 and n+4 are primes.

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A230715 Smallest numbers in a set of 4 consecutive odd numbers that are primes or pseudoprime (base 2).

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PARI

A230808 Smallest sets of 3 consecutive odd numbers that are primes or pseudoprime (base 2). The initial odd number is listed.

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Author

Keywords

Examples

Links

Crossrefs