A062179 Harmonic mean of digits is an integer.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 26, 33, 36, 44, 55, 62, 63, 66, 77, 88, 99, 111, 136, 144, 163, 222, 236, 244, 263, 288, 316, 326, 333, 346, 361, 362, 364, 414, 424, 436, 441, 442, 444, 463, 488, 555, 613, 623, 631, 632, 634, 643, 666, 777, 828, 848, 882, 884

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

1236 is a term as the harmonic mean is 4/(1+1/2+1/3+1/6) = 2.

Mathematica

Do[ h = IntegerDigits[n]; If[ Sort[h] [[1]] != 0 && IntegerQ[ Length[h] / Apply[ Plus, 1/h] ], Print[n]], {n, 1, 10^4} ] Note that the number of entries <= 10^n are 9, 22, 61, 198, 927, 4738, 24620, 130093,
hmdiQ[n_]:=DigitCount[n, 10, 0]==0&&IntegerQ[HarmonicMean[ IntegerDigits[ n]]]; Select[Range[1000], hmdiQ] (* Harvey P. Dale, Sep 22 2012 *)

Crossrefs

Cf. A062180-A062185, A061383-A061388, A061423-A061425.

Sequence in context: A107272 A039228 A161383 * A122875 A080716 A166461

Adjacent sequences: A062176 A062177 A062178 * A062180 A062181 A062182

Keyword

base,easy,nonn

Author

Vladeta Jovovic, Jun 12 2001

Extensions

More terms from Robert G. Wilson v, Aug 08 2001

Status

approved