OFFSET
1,1
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
FORMULA
EXAMPLE
13685 has sum of digits '23' and 13685 = 5*7*17*'23'.
MAPLE
A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc:
A006530 := proc(n) numtheory[factorset](n) ; max(op(%)) ; end proc:
for n from 1 to 8000 do if A007953(n) = A006530(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, May 30 2010
MATHEMATICA
Select[Range[2, 8000], FactorInteger[#][[-1, 1]]==Total[IntegerDigits[#]]&] (* Harvey P. Dale, Oct 17 2012 *)
PROG
(Haskell)
a052021 n = a052021_list !! (n-1)
a052021_list = tail $ filter (\x -> a007953 x == a006530 x) [1..]
-- Reinhard Zumkeller, Nov 06 2011
CROSSREFS
KEYWORD
nonn,base,nice
AUTHOR
Patrick De Geest, Nov 15 1999
EXTENSIONS
Single-digit primes added by R. J. Mathar, May 30 2010
Offset corrected by Reinhard Zumkeller, Nov 05 2011
STATUS
approved