This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A173689 Numbers n such that the sum of square of factorial of decimal digits is square.~ 0
 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 122, 202, 212, 220, 221, 244, 424, 442, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111, 2222, 3333, 3444, 4344, 4434, 4443, 4444, 5555, 6666, 6677, 6767, 6776, 6888, 7667, 7676, 7766, 7777, 8688, 8868, 8886, 8888, 9999 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Let the decimal expansion of n = d(0)d(1)…d(p). Numbers such that sum_{k=0..p}(d(k)!)^2   is square. LINKS EXAMPLE a(16) = 244 is in the sequence because (2!)^2 + (4!)^2 + (4!)^2 = 1156 = 34^2. MAPLE with(numtheory):for n from 0 to 10000 do:l:=length(n):n0:=n:s:=0:for m from   1 to l do:q:=n0:u:=irem(q, 10):v:=iquo(q, 10):n0:=v :s:=s+(u!)^2:od: q:=sqrt(s):if   floor(q)= q then printf(`%d, `, n):else fi:od: MATHEMATICA Select[Range[0, 10000], IntegerQ[Sqrt[Total[(IntegerDigits[#]!)^2]]]&] (* Harvey P. Dale, Dec 19 2011 *) CROSSREFS Sequence in context: A134853 A193407 A134810 * A004871 A059405 A191872 Adjacent sequences:  A173686 A173687 A173688 * A173690 A173691 A173692 KEYWORD nonn,base AUTHOR Michel Lagneau, Nov 25 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 10 04:15 EST 2019. Contains 329885 sequences. (Running on oeis4.)