cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

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%I A152080 #17 Dec 16 2018 06:40:51
%S A152080 55,77,87,91,115,117,121,171,185,203,213,253,299,327,329,369,405,415,
%T A152080 425,471,475,477,481,493,501,539,583,625,637,665,675,687,721,755,789,
%U A152080 803,805,815,817,833,835,841,855,861,913,935,955,973,979,981
%N A152080 Composite numbers c for which A000695(c) is prime.
%t A152080 f[n_] := FromDigits[IntegerDigits[n, 2], 4]; Select[Range[1000], CompositeQ[#] && PrimeQ[f[#]] &] (* _Amiram Eldar_, Dec 13 2018 *)
%o A152080 (PARI) a000695(n) = fromdigits(binary(n), 4);
%o A152080 lista(nn) = forcomposite(n=1, nn, if (isprime(a000695(n)), print1(n, ", "))); \\ _Michel Marcus_, Dec 13 2018
%Y A152080 Cf. A000695, A077718, A152021, A152022, A152023, A152078, A152079.
%K A152080 nonn
%O A152080 1,1
%A A152080 _Vladimir Shevelev_, Nov 23 2008
%E A152080 More terms derived from b000695.txt by _Michel Marcus_, Jun 02 2013