OFFSET
1,2
FORMULA
EXAMPLE
1! + 4! = 4! + 1! = 5^2, hence 14 and 41 are in the sequence.
MAPLE
A061602 := proc(n) local digs ; digs := convert(n, base, 10) ; add(factorial(op(i, digs)), i=1..nops(digs)) ; end: isA130687 := proc(n) issqr(A061602(n)) ; end: for n from 1 to 3000 do if isA130687(n) then printf("%d, ", n) ; fi ; od ; # R. J. Mathar, Jul 12 2007
MATHEMATICA
Select[Range[755], IntegerQ[Sqrt[DigitCount[ # ][[10]]+Sum[DigitCount[ # ][[i]]*i!, {i, 1, 9}]]] &]
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Yalcin Aktar, Jun 30 2007
EXTENSIONS
Edited by Stefan Steinerberger and R. J. Mathar, Jul 12 2007
STATUS
approved