A263106 Semiprimes such that the leftward cyclic permutation of its decimal digits is also semiprime.

4, 6, 9, 15, 22, 26, 33, 39, 49, 51, 55, 58, 62, 77, 85, 93, 94, 111, 122, 129, 134, 141, 145, 155, 158, 159, 161, 177, 178, 183, 185, 187, 202, 206, 214, 226, 254, 262, 298, 303, 309, 314, 321, 339, 341, 355, 358, 362, 371, 381, 391, 393, 394, 403, 407, 413

Offset

1,1

Comments

First 18 terms are also in A085751.

Links

Zak Seidov, Table of n, a(n) for n = 1..65049 (all terms up to 10^6)

Example

15 = 3 * 5, 51 = 3 * 17; 889 = 7 * 17, 898 = 2 * 449.

Mathematica

Select[Range[4, 1000], 2 == PrimeOmega[#] == PrimeOmega[FromDigits[RotateLeft[IntegerDigits[#]]]] &]

Prog

(PARI) shl(n)=if(n<10, return(n)); my(d=digits(n)); fromdigits(concat(d[2..#d], d[1]))
is(n)=bigomega(n)==2 && bigomega(shl(n))==2 \\ Charles R Greathouse IV, Oct 12 2015

Crossrefs

Cf. A001292, A001358, A085751.

Sequence in context: A251728 A078443 A085751 * A344468 A116589 A118688

Adjacent sequences: A263103 A263104 A263105 * A263107 A263108 A263109

Keyword

nonn,base

Author

Zak Seidov, Oct 09 2015

Status

approved