A062180 Harmonic mean of digits is 2.

2, 22, 136, 144, 163, 222, 316, 361, 414, 441, 613, 631, 1236, 1244, 1263, 1326, 1333, 1362, 1424, 1442, 1623, 1632, 2136, 2144, 2163, 2222, 2316, 2361, 2414, 2441, 2613, 2631, 3126, 3133, 3162, 3216, 3261, 3313, 3331, 3612, 3621, 4124, 4142, 4214, 4241

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

h:= proc(L) local m, x, i, t;
  m:= nops(L)+1;
  x:= m/2 - add(1/t, t=L);
  if x > 0 then
    x:= 1/x;
    if x::posint and x <= 9 then
      return(x + add(L[i]*10^i, i=1..m-1))
  fi fi
end proc:
f:= n -> h(map(`+`, convert(n, base, 9), 1)):
g:= n -> h([op(map(`+`, convert(n, base, 9), 1)), 1]):
R:= 2:
for d from 1 to 4 do
  R:= R, seq(f(i), i=9^(d-1)..9^d-1), seq(g(i), i=9^(d-1)..9^d-1)
od:
R; # Robert Israel, Apr 05 2021

Mathematica

Do[ h = IntegerDigits[n]; If[ Sort[h][[1]] != 0 && Length[h]/Apply[Plus, 1/h] == 2, Print[n]], {n, 1, 10^4}]

Crossrefs

Cf. A062179-A062185, A061383-A061388, A061423-A061425.

Sequence in context: A330900 A356341 A353191 * A244719 A084399 A067057

Adjacent sequences: A062177 A062178 A062179 * A062181 A062182 A062183

Keyword

base,easy,nonn

Author

Vladeta Jovovic, Jun 12 2001

Extensions

More terms from Henry Bottomley, Jul 25 2001

Status

approved