login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A262250 Primes having exactly one digit in {1, 3, 7, 9}. 1
3, 7, 23, 29, 41, 43, 47, 53, 59, 61, 67, 83, 89, 223, 227, 229, 241, 251, 257, 263, 269, 281, 283, 401, 409, 421, 443, 449, 457, 461, 463, 467, 487, 503, 509, 521, 523, 541, 547, 557, 563, 569, 587, 601, 607, 641, 643, 647, 653, 659, 661, 683, 809, 821, 823, 827, 829, 853, 857, 859, 863, 881, 883, 887, 2003, 2027, 2029, 2053 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
How can one prove that the sequence is infinite?
Probabilistic arguments imply that the number of terms not exceeding x is not less than 5/9*log(10)/log(6)*x^(log(6)/log(10))/log(x) = 0.7139...*x^0.778.../log(x).
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Prime@ Range@ 310, Total@ Drop[First /@ Partition[DigitCount@ #, 2, 2], {3}] == 1 &] (* Michael De Vlieger, Sep 21 2015 *)
PROG
(PARI) nbd(vd, d) = #select(i->(i == d), vd);
lista(nn) = {forprime(p=2, nn, vd = digits(p); if (nbd(vd, 1) + nbd(vd, 3) + nbd(vd, 7) + nbd(vd, 9) == 1, print1(p, ", ")); ); } \\ Michel Marcus, Sep 22 2015
(PARI) list(lim)=my(v=List([3])); forprime(p=7, lim, if(#setintersect(Set(digits(p\10)), [1, 3, 7, 9])==0, listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Sep 22 2015
(Perl) use ntheory ":all"; say join ", ", grep { tr/1379// == 1 } @{primes(3000)}; # Dana Jacobsen, Oct 13 2015
CROSSREFS
Sequence in context: A225264 A032403 A072584 * A139513 A144593 A057191
KEYWORD
nonn,base
AUTHOR
Vladimir Shevelev, Sep 21 2015
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)