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A257830
The decimal representation of the geometric mean of the digits of n starts with the digits of n.
4
1, 2, 3, 4, 5, 6, 7, 8, 9, 34, 79, 215, 437, 2514, 3833, 32453, 35194, 49672, 5695449, 357129525, 44683966971145538, 383375167535817138, 4377829714163336859592836
OFFSET
1,2
COMMENTS
a(24) > 10^30.
MATHEMATICA
pr[n_] := Union@Flatten@ Table[Union[ Times @@@ Flatten[Outer[Power, Subsets[ Range@9, {Length@e}], Permutations[e], 1], 1]], {e, IntegerPartitions@ n}]; sol[nd_] := Block[{p = ppr[nd], L}, L = Table[FromDigits[ RealDigits[x^(1/nd), 10, nd][[1]]], {x, p}]; L[[Select[Range@Length@p, Times @@ IntegerDigits[L[[#]]] == p[[#]] &]]]]; Union@ Flatten@ Array[sol, 17] (* terms with up to 17 digits *)
PROG
(PARI) is(n)=n==sqrtn(prod(i=1, #n=digits(n), n[i]), #n)\10^(1-#n) \\ M. F. Hasler, May 10 2015
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Giovanni Resta, May 10 2015
STATUS
approved