A077718 -id:A077718 - cp's OEIS frontend

A152080 Composite numbers c for which A000695(c) is prime.

55, 77, 87, 91, 115, 117, 121, 171, 185, 203, 213, 253, 299, 327, 329, 369, 405, 415, 425, 471, 475, 477, 481, 493, 501, 539, 583, 625, 637, 665, 675, 687, 721, 755, 789, 803, 805, 815, 817, 833, 835, 841, 855, 861, 913, 935, 955, 973, 979, 981

Offset: 1

Vladimir Shevelev, Nov 23 2008

nonn

Cf. A000695, A077718, A152021, A152022, A152023, A152078, A152079.

f[n_] := FromDigits[IntegerDigits[n, 2], 4]; Select[Range[1000], CompositeQ[#] && PrimeQ[f[#]] &] (* Amiram Eldar, Dec 13 2018 *)

a000695(n) = fromdigits(binary(n), 4);
lista(nn) = forcomposite(n=1, nn, if (isprime(a000695(n)), print1(n, ", "))); \\ Michel Marcus, Dec 13 2018

More terms derived from b000695.txt by Michel Marcus, Jun 02 2013

A152863 Numbers for which A000695(p_n) are primes, where p_n is the n-th prime.

Original entry on oeis.org

2, 3, 7, 9, 10, 14, 15, 16, 18, 23, 28, 34, 35, 36, 40, 41, 42, 43, 50, 51, 52, 55, 56, 57, 59, 63, 71, 75, 76, 77, 80, 85, 86, 87, 92, 96, 103, 104, 115, 118, 119, 121, 122, 132, 138, 143, 150, 151, 158, 163, 166, 175, 176, 180, 181, 196, 202, 204, 205, 206, 208

Offset: 1

Vladimir Shevelev, Dec 14 2008

nonn

Cf. A152078, A077718.

a000695(n) = fromdigits(binary(n), 4);
isok(n) = isprime(a000695(prime(n))); \\ Michel Marcus, Dec 18 2018

More terms from Michel Marcus, Dec 18 2018

cp's OEIS Frontend

A152080 Composite numbers c for which A000695(c) is prime.

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