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 A227795 For each base, b, beginning with binary, the number of (b-1)-digit primes with one copy of each digit save one. 0
 0, 3, 1, 9, 52, 283, 2113, 16142, 145227, 1359133, 15000161, 172888810, 2217146126 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 COMMENTS Note that only decimal 2, 11 and 19 are representable in some base using a copy of each digit in that base (base 2 for the first and base 3 for the others), as a number written in base b with a single copy of each digit is congruent to either 0 or (b-1)/2 modulo b-1. LINKS EXAMPLE In base 3, 10, 12 and 21 are primes: Decimal 3, 5 and 7.  In base 4, of the possibilities only 103 is prime: Decimal 19. PROG (PARI) \\ Starts at base 4 and prints in form 'base:count', bases 2 and 3 done by hand. { b=4; while(1, c=0; for(i=1, b!, perm=numtoperm(b, i); if(perm[b-1]!=1, if(gcd(b, perm[1]-1)==1, if(gcd(b-1, perm[b]-1)==1, n=sum(j=1, b-1, (perm[j]-1)*b^(j-1)); if(ispseudoprime(n), c++))))); print1(b":"c"\n"); b++) } CROSSREFS Cf. A073643, A116670. Sequence in context: A105951 A038202 A128415 * A090479 A227758 A304638 Adjacent sequences:  A227792 A227793 A227794 * A227796 A227797 A227798 KEYWORD nonn,base,less AUTHOR James G. Merickel, Sep 23 2013 EXTENSIONS a(14) added by James G. Merickel, Oct 14 2013 STATUS approved

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Last modified November 26 09:38 EST 2020. Contains 338639 sequences. (Running on oeis4.)