login
This site is supported by donations to The OEIS Foundation.

 

Logo

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A214285 Amicable sums-of-factorial-of-digits pairs (A,B): A equals the sum of the factorials of B's digits in base 10, and vice versa. 1
871, 45361, 872, 45362 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Number pairs (A,B), A<> B, such that A061602(A)=B and A061602(B)=A, indicating where the mapping of A to the sum of the factorials of its digits has a cycle of length 2.

LINKS

Table of n, a(n) for n=1..4.

Jaeyool Park, Blog

Project Euler, Problem 74

EXAMPLE

8! + 7! + 1! = 45361, 4! + 5! + 3! + 6! + 1! = 871.

MAPLE

with(numtheory);

A214285:=proc(q)

local a, b, c, d, i, n;

for n from 1 to q do

  a:=n; b:=0; while a>0 do b:=b+1; a:=trunc(a/10); od; a:=n; c:=0; d:=0;

  for i from 1 to b do  c:=c+(a-trunc(a/10)*10)!; a:=trunc(a/10); od;

  a:=c; b:=0; while a>0 do b:=b+1; a:=trunc(a/10); od; a:=c;

  for i from 1 to b do  d:=d+(a-trunc(a/10)*10)!; a:=trunc(a/10); od;

  if n=d and n<>c then lprint(n, c); fi;

od; end:

A214285(1000000000000) # Paolo P. Lava, Jul 10 2012.

CROSSREFS

Cf. A014080, A188284

Sequence in context: A035855 A031783 A253167 * A251841 A251085 A206312

Adjacent sequences:  A214282 A214283 A214284 * A214286 A214287 A214288

KEYWORD

nonn,base,tabf

AUTHOR

Jaeyool Park, Jul 10 2012

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 17 16:51 EDT 2017. Contains 290648 sequences.