A155053 Primes n with nonprime smallest digit of prime(n).
5, 7, 11, 13, 19, 29, 31, 37, 41, 43, 47, 53, 67, 79, 83, 89, 97, 101, 113, 127, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 347, 349, 353, 359, 379, 397, 409, 421, 431, 433, 439, 443, 449, 467, 479, 491, 523, 541, 557, 563, 569, 571, 577, 601, 613, 617, 619, 641, 643, 647, 653, 673, 677, 683, 691, 701, 709, 719, 727, 743, 751, 757, 761, 769
Offset: 1
Examples
a(1) = 5 corresponds to the fact that the fifth prime is 11, the smallest digit of which is 1, which is nonprime. a(2) = 7: the seventh prime is 17, the smallest digit of which is 1, which is nonprime. a(3) = 11: the eleventh prime is 31, the smallest digit of which is 1, which is, again, nonprime.
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Crossrefs
Cf. A154981.
Programs
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Mathematica
Select[Prime[Range[150]], !PrimeQ[Min[IntegerDigits[Prime[#]]]] &] (* Harvey P. Dale, Nov 25 2010 *)
Extensions
Corrected (19 inserted, 1673 replaced by 167) by R. J. Mathar, May 05 2010
More terms from Harvey P. Dale, Nov 25 2010