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

Author

Enoch Haga, Dec 13 2001

Keywords

• easy
• nonn
• base

Comments

No further terms found to 10^8.

Examples

			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]
		

Links

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

Crossrefs

Cf. A066042.

Programs

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 *)

PARI

{ for(k=0, 10^7, my(d=digits(k), q=vecsum(d)*vecprod(d)); if (q != 0 && k%q==0 && isprime(k/q), print1(k/q, ", "))) } \\ Harry J. Smith, Feb 02 2010

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

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