A066613 Numbers k such that the product of the nonzero digits of k equals the number of divisors of k.
1, 2, 14, 22, 24, 32, 42, 116, 122, 126, 141, 202, 211, 221, 222, 260, 280, 340, 402, 411, 440, 512, 620, 840, 1021, 1041, 1062, 1114, 1118, 1128, 1132, 1141, 1144, 1201, 1202, 1206, 1218, 1222, 1242, 1250, 1314, 1332, 1340, 1380, 1401, 1411, 1602, 1611
Offset: 1
Examples
24 is a term as there are 8 divisors of 24 = 2*4.
Links
- Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 1000 terms from Harry J. Smith)
Programs
-
Mathematica
f[n_] := Block[ {a = Sort[ IntegerDigits[n]] }, While[ First[a] == 0, a = Drop[a, 1]]; Return[ Apply[ Times, a]]]; Select[ Range[10^4], f[ # ] == Length[ Divisors[ # ]] & ] pndQ[n_]:=Times@@Select[IntegerDigits[n],#!=0&]==DivisorSigma[0,n]; Select[Range[2000],pndQ] (* Harvey P. Dale, Oct 25 2016 *) -
PARI
isok(k) = { vecprod(select(x->(x!=0), digits(k))) == numdiv(k) } \\ Harry J. Smith, Mar 12 2010
Extensions
Corrected and extended by Jason Earls and Robert G. Wilson v, Dec 26 2001
Comments