A174570 - OEIS

A174570

Numbers n such that sum of squares of factorials of digits of n is a power of 2.

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

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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