OFFSET
1,1
COMMENTS
Also primes that terminate at 4,2,1 in the x-1 problem: Repeat, if x is even divide by 2 else subtract 1, until 4 is reached. - Cino Hilliard, Mar 27 2003
David W. Wilson remarks that it follows from standard results about primes in short intervals (see for example Harman, 1982) that there are infinitely many numbers in any base b starting with any nonzero prefix c. - N. J. A. Sloane, Sep 19 2015
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..20000
G. Harman, Primes in short intervals, Math. Zeit., 180 (1982), 335-348.
EXAMPLE
A000040(15)=47 -> '101111' therefore 47 is a term.
MATHEMATICA
Select[Prime[Range[1000]], IntegerDigits[#, 2][[;; 2]] == {1, 0}&] (* Jean-François Alcover, Oct 25 2021 *)
PROG
(PARI) pxnm1(n, p) = { forprime(x=2, n, p1 = x; while(p1>1, if(p1%2==0, p1/=2, p1 = p1*p-1; ); if(p1 == 4, break); ); if(p1 == 4, print1(x" ")) ) }
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Feb 03 2003
STATUS
approved