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A241013 Semiprimes congruent to {1, 2, 4} mod 5. 1
4, 6, 9, 14, 21, 22, 26, 34, 39, 46, 49, 51, 57, 62, 69, 74, 77, 82, 86, 87, 91, 94, 106, 111, 119, 121, 122, 129, 134, 141, 142, 146, 159, 161, 166, 169, 177, 187, 194, 201, 202, 206, 209, 214, 217, 219, 221, 226, 237, 247, 249, 254, 259, 262, 267, 274, 287, 289 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Semiprimes in A032793.

LINKS

K. D. Bajpai, Table of n, a(n) for n = 1..11280

EXAMPLE

21 = 3 * 7 which is semiprime and 21 = 1 mod 5.

39 = 3 * 13 which is semiprime and 39 = 4 mod 5.

MATHEMATICA

Select[Range[500], PrimeOmega[#] == 2 && MemberQ[{1, 2, 4}, Mod[#, 5]] &](* Bajpai *)

Select[Complement[Range[100], 5Range[20] - 2, 5Range[20]], PrimeOmega[#] == 2 &] (* Alonso del Arte, Aug 07 2014 *)

PROG

(PARI)

for(n=1, 10^4, if(n!=Mod(0, 5)&&n!=Mod(3, 5), if(bigomega(n)==2, print1(n, ", ")))) \\ Derek Orr, Aug 07 2014

CROSSREFS

Cf. A001358, A032793, A045371.

Sequence in context: A286303 A084336 A094750 * A057988 A175587 A175709

Adjacent sequences:  A241010 A241011 A241012 * A241014 A241015 A241016

KEYWORD

nonn,easy

AUTHOR

K. D. Bajpai, Aug 07 2014

STATUS

approved

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Last modified April 22 22:38 EDT 2019. Contains 322380 sequences. (Running on oeis4.)