A066521 Primes p(k) such that the product of digits of p(k) equals the product of digits of k.

17, 181, 443, 491, 1163, 2131, 2143, 2153, 2621, 4253, 4621, 7691, 11483, 11593, 11813, 23819, 26951, 27179, 32261, 32443, 33811, 35171, 35227, 37643, 41543, 42433, 42443, 44623, 44917, 45971, 51473, 54517, 58193, 61223, 63131, 64591

Offset

1,1

Comments

Numbers with product of digits=0, like prime(80) = 409, are not included. - Harry J. Smith, Feb 20 2010

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Example

181 is the 42nd prime and the product of digits of both is 8.

Mathematica

Select[Table[{n, Prime[n]}, {n, 6500}], DigitCount[#[[1]], 10, 0]==0 && Times@@ IntegerDigits[#[[1]]]==Times@@IntegerDigits[#[[2]]]&][[All, 2]] (* Harvey P. Dale, Oct 17 2020 *)

Prog

(PARI) ProdD(x)= { local(p=1); while (x>9 && p>0, p*=x%10; x\=10); return(p*x) } { n=0; for (m=1, 10^10, p=prime(m); d=ProdD(m); if (ProdD(p) == d && d, write("b066521.txt", n++, " ", p); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 20 2010

Crossrefs

Cf. A007954, A033548.

Sequence in context: A342198 A130651 A142214 * A055904 A116964 A167578

Adjacent sequences: A066518 A066519 A066520 * A066522 A066523 A066524

Keyword

base,less,nonn

Author

Jason Earls, Jan 05 2002

Status

approved