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A263106
Semiprimes such that the leftward cyclic permutation of its decimal digits is also semiprime.
3
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
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Oct 09 2015
STATUS
approved