login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A202242 n such that the sum of digit !! of n equals the sum of d|n, 1<d<n. 0

%I #11 Mar 30 2012 18:36:00

%S 14,56,28361,119507,191557,287039,691259,750889

%N n such that the sum of digit !! of n equals the sum of d|n, 1<d<n.

%C No further terms less than 10^8.

%C The double factorial n!! (A006882) of a positive integer n is the product of the positive integers <= n that have the same parity as n.

%e 56 is in the sequence because 5!! + 6!! = 15 + 48 = 63, and sum of the divisors 1< d< 56 = sigma(56) - 56 - 1 = 120 - 56 - 1 = 63.

%t Q[n_]:=Module[{a=Total[Rest[Most[Divisors[n]]]]}, a == Total[IntegerDigits[n]!!]]; Select[Range[2, 10^5], Q]

%Y Cf. A006882, A048050.

%K nonn,hard,base

%O 1,1

%A _Michel Lagneau_, Dec 16 2011

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 17 17:01 EDT 2024. Contains 371765 sequences. (Running on oeis4.)