A155785 Nonprimes where the first digit equals the final digit and also equals the number of digits.

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

Links

Table of n, a(n) for n=1..44.

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

Adjacent sequences: A155782 A155783 A155784 * A155786 A155787 A155788

Keyword

nonn,base,fini

Author

Juri-Stepan Gerasimov, Jan 27 2009

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