

A154539


Primes p such that (smallest digit of p) + (number of occurrences of smallest digit of p) is prime.


0



2, 11, 13, 17, 19, 23, 29, 31, 41, 47, 61, 67, 71, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 311, 313, 317, 331, 337, 353, 373, 383, 419, 421, 431, 433
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..55.


EXAMPLE

2 is the smallest digit of 2, and it appears once; 2 and 2+1 are prime, so a(1) = 2.
1 is the smallest digit of 11 and it appears twice; 11 and 1+2 are prime, so a(2) = 11.
1 is the smallest digit of 13 and it appears once; 13 and 1+1 are prime, so a(3) = 13.


MAPLE

frequdig := proc(n, dig) local f, d ; f := 0 ; for d in convert(n, base, 10) do if d = dig then f :=f+1; end if; end do; f ; end proc:
A054054 := proc(n) min(op(convert(n, base, 10)) ) ; end proc:
for n from 1 to 500 do p := ithprime(n) ; sdg := A054054(p) ; a := sdg +frequdig(p, sdg) ; if isprime(a) then printf("%d, ", p ) ; end if; end do: # R. J. Mathar, May 05 2010


CROSSREFS

Sequence in context: A116437 A048867 A113626 * A137238 A048521 A172071
Adjacent sequences: A154536 A154537 A154538 * A154540 A154541 A154542


KEYWORD

nonn,base,less


AUTHOR

JuriStepan Gerasimov, Jan 11 2009


EXTENSIONS

Entries checked by R. J. Mathar, May 05 2010


STATUS

approved



