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A174570 Numbers n such that sum of squares of factorials of digits of n is a power of 2. 1
1, 2, 10, 11, 22, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111, 2222, 10002, 10012, 10020, 10021, 10102, 10112, 10120, 10121, 10200, 10201, 10210, 10211, 11002, 11012, 11020, 11021, 11102, 11112, 11120, 11121, 11200, 11201, 11210, 11211, 12000, 12001, 12010, 12011, 12100, 12101, 12110, 12111, 20000, 20001, 20010 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

10012 is in the sequence because (1!)^2 +(0!)^2 +(0!)^2 +(1!)^2 +(2!)^2 = 8 = 2^3.

MAPLE

with(numtheory):for n from 1 to 100000 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:= evalf(log[2](s));

  if floor(q)= q then printf(`%d, `, n):else fi:od:

PROG

(Sage) A174570 = list(n for n in IntegerRange(1, 10**5) if sum(factorial(d)**2 for d in n.digits()).is_power_of(2))

CROSSREFS

Sequence in context: A069263 A174569 A179884 * A072545 A023151 A342535

Adjacent sequences:  A174567 A174568 A174569 * A174571 A174572 A174573

KEYWORD

nonn,base

AUTHOR

Michel Lagneau, Nov 29 2010

STATUS

approved

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Last modified May 18 13:09 EDT 2021. Contains 343995 sequences. (Running on oeis4.)