OFFSET
1,2
EXAMPLE
223623 is in the sequence because 1/2^2 + 1/2^2 + 1/3^2 + 1/6^2 + 1/2^2 + 1/3^2 = 1 is integer.
MAPLE
T:=array(1..10):for n from 1 to 10^7 do:T:=convert(n, base, 10):n1:=nops(T): s:=0:j:=0:for k from 1 to n1 do:if T[k]<>0 then s:=s+evalf(1/T[k]^2):else j:=1:fi: od: if j=0 and s=floor(s) then printf(`%d, `, n):else fi:od:
MATHEMATICA
f[ n_ ] := 1/n^2; a[ n_ ] := Apply[ Plus, Map[ f, IntegerDigits[ n ] ] ] ; Select[ Range[ 1000 ], FreeQ[ IntegerDigits[ # ], 0 ] && IntegerQ[ a [ # ] ] & ]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Lagneau, Apr 29 2012
STATUS
approved