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A104179
Primes that are either single-digit primes or a concatenation of two earlier terms.
4
2, 3, 5, 7, 23, 37, 53, 73, 223, 233, 337, 353, 373, 523, 733, 773, 2237, 2333, 3373, 3533, 3733, 5233, 5237, 5323, 7333, 7523, 23333, 23773, 25237, 32237, 33533, 33773, 35323, 35353, 37223, 37337, 52237, 53233, 53353, 53773, 73523, 75323, 77323
OFFSET
1,1
LINKS
Karl W. Heuer, Table of n, a(n) for n = 1..13849 (first 1003 terms from Jean-Marc Falcoz)
FORMULA
Up to 10^12 there are only 1003 terms and the n-th term seems to be roughly n^(10/e). - Jean-Marc Falcoz, Mar 28 2009
Although the n-th term does seem to be O(n^c), a better estimate for c is 4.38 rather than 10/e. The multiplier will be bounded but not convergent -- it jumps by a factor of 20/7 as we cross from a k-digit number beginning 777 to a (k+1)-digit number beginning 2222. - Karl W. Heuer, Sep 23 2024
PROG
(PARI) isDW(p, i=1)={while(p>i*=10, setminus(Set(divrem(p, i)), a)||return(eval(Set(Vec(Str(p)))[1]))); p<9}
a=[]; forprime( p=2, 99999, isDW(p) & !print1(p", ") & a=setunion(a, Set(p))) \\ M. F. Hasler, Mar 28 2009
CROSSREFS
Cf. A376433 (number of n-digit terms), A376434 (smallest n-digit term), A376435 (largest n-digit term).
Sequence in context: A154385 A125525 A019546 * A096148 A211681 A124674
KEYWORD
nonn,base,changed
AUTHOR
David W. Wilson, Mar 27 2009
EXTENSIONS
More terms from M. F. Hasler, Mar 28 2009
STATUS
approved