A103796 -id:A103796 - cp's OEIS frontend

A103797 Indices of n such that A019565(n)-1 is prime.

2, 3, 7, 9, 11, 21, 27, 29, 31, 39, 41, 47, 51, 53, 55, 61, 63, 67, 71, 81, 89, 91, 107, 113, 121, 123, 129, 131, 135, 139, 143, 149, 151, 157, 159, 163, 169, 175, 179, 183, 187, 191, 197, 199, 207, 211, 217, 223, 235, 241, 251, 259, 261, 269, 279, 281, 287, 295

Offset: 0

Lei Zhou, Feb 22 2005

nonn

			A019565(0)=1, 1-1=0 is not prime;
A019565(1)=2, 2-1=1 is not prime;
A019565(2)=3, 3-1=2 is prime, so a(1)=2.

Cf. A019565, A103796.

A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[cp = A019565[n] - 1; If[PrimeQ[cp], Print[n]], {n, 0, 1000}]

A103799 Indices n such that A019565(n)+2 is prime.

Original entry on oeis.org

0, 2, 4, 6, 10, 12, 14, 16, 22, 24, 26, 34, 36, 38, 44, 46, 50, 62, 64, 66, 70, 74, 78, 82, 84, 90, 92, 96, 104, 106, 116, 118, 124, 130, 132, 138, 142, 144, 150, 154, 162, 164, 170, 172, 176, 186, 190, 194, 224, 230, 242, 252, 258, 262, 264, 270, 274, 278, 302, 308

Offset: 1

Lei Zhou, Feb 22 2005

			A019565(0)=1, 1+2=3 is prime, so a(1)=0;
A019565(1)=2, 2+2=4 is not prime,
A019565(2)=3, 3+2=5 is prime, so a(2)=2;

Cf. A019565, A103796, A103797.

A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[cp = A019565[n] + 2; If[PrimeQ[cp], Print[n]], {n, 0, 1000}]

A103798 Integers k such that A019565(k)-1 and A019565(k)+1 are both primes.

Original entry on oeis.org

3, 7, 11, 27, 31, 47, 51, 67, 107, 123, 135, 151, 159, 163, 175, 211, 251, 259, 279, 295, 479, 527, 539, 607, 619, 631, 771, 783, 847, 999, 1035, 1051, 1071, 1183, 1279, 1295, 1299, 1323, 1375, 1399, 1411, 1439, 1451, 1479, 1571, 1691, 1715, 1759, 1787, 1991

Offset: 1

Lei Zhou, Feb 22 2005

Amiram Eldar, Table of n, a(n) for n = 1..10000

Cf. A019565, A103796, A103797.

A019565(3) = 6, 5 and 7 are twin primes, so a(1) = 3.
A019565(7) = 30, 29 and 31 are twin primes, so a(2) = 7.

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A103797 Indices of n such that A019565(n)-1 is prime.

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A103799 Indices n such that A019565(n)+2 is prime.

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A103798 Integers k such that A019565(k)-1 and A019565(k)+1 are both primes.

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