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A217790 Composite evil numbers (A001969) having no proper evil divisors. 2
77, 169, 209, 287, 329, 343, 407, 413, 427, 469, 533, 553, 649, 679, 703, 763, 869, 893, 917, 931, 1121, 1133, 1169, 1253, 1271, 1331, 1337, 1351, 1369, 1391, 1393, 1457, 1477, 1501, 1517, 1589, 1631, 1661, 1757, 1781, 1813, 1829, 1963, 1991, 2033, 2191, 2209 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence is obtained using Eratosthenes-like sieve for evil numbers.

a(10^2) = 4367, a(10^3) = 40247, a(10^4) = 407659, a(10^5) = 4434067. - Giovanni Resta, Mar 28 2013

LINKS

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

MATHEMATICA

evilQ[n_] := EvenQ@Total@IntegerDigits[n, 2]; okQ[n_] := evilQ[n] && ! PrimeQ[n] && Catch[Do[If[evilQ[d], Throw[False]], {d, Most@Rest@Divisors@n}]; True]; Select[Range@3000, okQ] (* Giovanni Resta, Mar 28 2013 *)

PROG

(PARI) isevil(n) = hammingweight(n) % 2 == 0;

noevildiv(n) = {fordiv(n, d, if ((d < n) && isevil(d), return (0)); ); 1; }

lista(nn) = {forcomposite(n=1, nn, if (isevil(n) && noevildiv(n), print1(n, ", ")); ); } \\ Michel Marcus, Feb 08 2016

CROSSREFS

Cf. A000069, A001969.

Sequence in context: A338189 A308963 A075253 * A046513 A199994 A043518

Adjacent sequences:  A217787 A217788 A217789 * A217791 A217792 A217793

KEYWORD

nonn,base

AUTHOR

Vladimir Shevelev, Mar 28 2013

STATUS

approved

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Last modified September 24 21:51 EDT 2022. Contains 356949 sequences. (Running on oeis4.)