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A066146 Primes associated with A066042. 2

%I

%S 2,37,2,2,571,47,3,3,103,61,113,97,797,41893,499,109,701,997,1231,47,

%T 1801,557,1129,7481,15731,32579,491,257,23,24551,8753,110339,3119,

%U 10133,46811,4799,5233,215389,1049,1063039,64327,349,2477,69827,317,107377

%N Primes associated with A066042.

%C No further terms found to 10^8.

%H Harry J. Smith, <a href="/A066146/b066146.txt">Table of n, a(n) for n = 1..54</a>

%F Sum digits of n; find product of digits of n; multiply sum by product; divide this product into n; if result is prime add to sequence

%e a(5)=571 because 4+1+1+1+2=9 and 4*2=8; 8*9=72; 41112/72 = 571 and 571 is prime. [corrected by _Harry J. Smith_, Feb 02 2010]

%t rp[n_]:=Module[{idn=IntegerDigits[n],p},If[MemberQ[idn,0],p=1,p=n/ (Total[ idn] Times@@idn)];If[PrimeQ[p],p,0]]; DeleteCases[ rp/@ Range[ 10^8],0] (* _Harvey P. Dale_, Jan 03 2015 *)

%o (PARI) ProdD(x)= { local(p=1); while (x>9 && p>0, p*=x%10; x\=10); return(p*x) } SumD(x)= { local(s=0); while (x>9, s+=x%10; x\=10); return(s + x) } { n=0; for (m=1, 10^12, p=ProdD(m); if (p == 0, next); f=m/(SumD(m)*p); if (frac(f)==0 && isprime(f), write("b066146.txt", n++, " ", f); if (n==54, return)) ) } \\ _Harry J. Smith_, Feb 02 2010

%Y Cf. A066042.

%K easy,nonn,base

%O 1,1

%A _Enoch Haga_, Dec 13 2001

%E Offset changed from 2 to 1 by _Harry J. Smith_, Feb 02 2010

%E a(32)-a(46) from _Harry J. Smith_, Feb 02 2010

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Last modified December 2 11:44 EST 2021. Contains 349440 sequences. (Running on oeis4.)