A066146 Primes associated with A066042.

2, 37, 2, 2, 571, 47, 3, 3, 103, 61, 113, 97, 797, 41893, 499, 109, 701, 997, 1231, 47, 1801, 557, 1129, 7481, 15731, 32579, 491, 257, 23, 24551, 8753, 110339, 3119, 10133, 46811, 4799, 5233, 215389, 1049, 1063039, 64327, 349, 2477, 69827, 317, 107377

Offset

1,1

Comments

No further terms found to 10^8.

Links

Harry J. Smith, Table of n, a(n) for n = 1..54

Formula

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

Example

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]

Mathematica

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 *)

Prog

(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

Crossrefs

Cf. A066042.

Sequence in context: A078081 A077772 A083150 * A258035 A178200 A049106

Adjacent sequences: A066143 A066144 A066145 * A066147 A066148 A066149

Keyword

easy,nonn,base

Author

Enoch Haga, Dec 13 2001

Extensions

Offset changed from 2 to 1 by Harry J. Smith, Feb 02 2010

a(32)-a(46) from Harry J. Smith, Feb 02 2010

Status

approved