A066310 Numbers k such that k < (product of digits of k) * (sum of digits of k).

2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 23, 24, 25, 26, 27, 28, 29, 33, 34, 35, 36, 37, 38, 39, 42, 43, 44, 45, 46, 47, 48, 49, 52, 53, 54, 55, 56, 57, 58, 59, 62, 63, 64, 65, 66, 67, 68, 69, 72, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 92, 93, 94, 95

Offset

1,1

Links

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

Example

14 < (1*4)*(1+4) = 20, so 14 is a term of this sequence.
For n=199, (1+9+9)*1*9*9 = 1539 > 199, so 199 is here.

Mathematica

asum[x_] := Apply[Plus, IntegerDigits[x]] apro[x_] := Apply[Times, IntegerDigits[x]] sz[x_] := asu[x]*apro[x] Do[s=sz[n]; If[Greater[s, n], Print[n]], {n, 1, 200}]

Prog

(ARIBAS): function a066311(a, b: integer); var n, k, j, p, d: integer; s: string; begin for n := a to b do s := itoa(n); k := 0; p := 1; for j := 0 to length(s) - 1 do d := atoi(s[j..j]); k := k + d; p := p*d; end; if n < p*k then write(n, ", "); end; end; end; a066311(0, 120).
(PARI) isok(m) = my(d=digits(m)); m < vecprod(d)*vecsum(d); \\ Michel Marcus, Mar 23 2020

Crossrefs

Cf. A038369, A049101-A049106, A034710, A061672, A066306-A066309.

Sequence in context: A290950 A032577 A244155 * A342226 A032987 A174876

Adjacent sequences: A066307 A066308 A066309 * A066311 A066312 A066313

Keyword

base,nonn,fini

Author

Labos Elemer and Klaus Brockhaus, Dec 13 2001

Status

approved