A155034 Primes with smallest digit odd and prime (i.e., 3, 5 or 7).

3, 5, 7, 37, 43, 53, 59, 73, 79, 83, 97, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 433, 439, 443, 463, 557, 563, 569, 577, 587, 593, 599, 643, 653, 659, 673, 683, 733, 739, 743, 757, 773, 787, 797, 839, 853, 857, 859, 863, 877, 883, 887, 937, 953, 977

Offset

1,1

Comments

Primes p such that A054054(p) is in the set {3, 5, 7}. - Felix Fröhlich, Jan 26 2017

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

N:= 4: # to get all terms with <+ N digits
for j in [3, 5, 7] do L[1, j]:= {$j..9}; C[1, j]:= {j} od;
for d from 2 to N do
  for j in [3, 5, 7] do L[d, j]:= map(t -> $(10*t+j)..(10*t+9), L[d-1, j]) od:
  C[d, 3]:= map(t -> (10*t+3), L[d-1, 3]) union map(t ->seq(10*t+j, j=4..9), C[d-1, 3]);
  C[d, 5]:= map(t -> (10*t+5), L[d-1, 5]) union map(t -> seq(10*t+j, j=6..9), C[d-1, 5]);
  C[d, 7]:= map(t -> (10*t+7), L[d-1, 7]) union map(t -> seq(10*t+j, j=8..9), C[d-1, 7]);
od:
sort(convert(`union`(seq(seq(select(isprime, C[d, j]), j=[3, 5, 7]), d=1..N)), list));
# Robert Israel, Jan 26 2017

Prog

(PARI) is(n) = ispseudoprime(n) && #setintersect(Set(vecmin(digits(n))), [3, 5, 7])==1 \\ Felix Fröhlich, Jan 26 2017

Crossrefs

Cf. A000040, A054054.

Sequence in context: A327413 A106115 A154544 * A126359 A182373 A087363

Adjacent sequences: A155031 A155032 A155033 * A155035 A155036 A155037

Keyword

nonn,base,less

Author

Juri-Stepan Gerasimov, Jan 19 2009

Extensions

Edited by N. J. A. Sloane, Jan 24 2009

Corrected by Robert Israel, Jan 26 2017

Status

approved