A074312 Numbers k such that the product of the digits of k equals the number of divisors of k.

1, 2, 14, 22, 24, 32, 42, 116, 122, 126, 141, 211, 221, 222, 411, 512, 1114, 1118, 1128, 1132, 1141, 1144, 1218, 1222, 1242, 1314, 1332, 1411, 1611, 1612, 2111, 2114, 2132, 2214, 2232, 2312, 2511, 3114, 3211, 3212, 4116, 4131, 4312, 6112, 8211

Offset

1,2

Links

Giovanni Resta, Table of n, a(n) for n = 1..10000

Example

24 is a term as the product of the digits of 24 is 2*4 = 8 and the number of divisors = 8.

Maple

with(numtheory):l := 1:a[1] := 1:for n from 2 to 10000 do d := convert(n, base, 10): if(product(d[i], i=1..nops(d))=tau(n)) then l := l+1:a[l] := n:fi:od:seq(a[i], i=1..l); # Sascha Kurz

Mathematica

Select[Range[10^4], Apply[Times, IntegerDigits[ # ]] == DivisorSigma[0, # ] &]

Crossrefs

Cf. A057531, A066613.

Sequence in context: A335071 A073143 A066613 * A061426 A190045 A247035

Adjacent sequences: A074309 A074310 A074311 * A074313 A074314 A074315

Keyword

base,easy,nonn

Author

Joseph L. Pe, Sep 22 2002

Status

approved