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A152080 Composite numbers c for which A000695(c) is prime. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..50.

MATHEMATICA

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

PROG

(PARI) a000695(n) = fromdigits(binary(n), 4);

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

CROSSREFS

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

Sequence in context: A217236 A050781 A060260 * A236769 A119224 A135984

Adjacent sequences:  A152077 A152078 A152079 * A152081 A152082 A152083

KEYWORD

nonn

AUTHOR

Vladimir Shevelev, Nov 23 2008

EXTENSIONS

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

STATUS

approved

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Last modified May 19 04:06 EDT 2019. Contains 323377 sequences. (Running on oeis4.)