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A155785
Nonprimes where the first digit equals the final digit and also equals the number of digits.
0
1, 22, 303, 323, 333, 343, 363, 393, 4004, 4014, 4024, 4034, 4044, 4054, 4064, 4074, 4084, 4094, 4104, 4114, 4124, 4134, 4144, 4154, 4164, 4174, 4184, 4194, 4204, 4214, 4224, 4234, 4244, 4254, 4264, 4274, 4284, 4294, 4304, 4314, 4324, 4334, 4344, 4354
OFFSET
1,2
COMMENTS
Subsequence of A018252.
Sequence is finite; last term is a(9885995) = 999999999. - Charles R Greathouse IV, Dec 30 2012
PROG
(PARI) is(n)=my(d=digits(n)); !isprime(n) && d[1]==n%10 && d[1] == #d \\ Charles R Greathouse IV, Dec 29 2012
CROSSREFS
Sequence in context: A333063 A022746 A125457 * A077525 A083765 A061341
KEYWORD
nonn,base,fini
AUTHOR
EXTENSIONS
The definition was unclear, but I have made a guess as to what was intended. - N. J. A. Sloane, Feb 02 2009
Added requirement on digit count to the definition R. J. Mathar, Feb 13 2009
STATUS
approved