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A300487 Numbers k whose 10's complement mod 10 of their digits is equal to phi(k), the Euler totient function of k. 0
74, 834, 80940, 809400, 833334, 7414114, 7422694, 7539694, 8094000, 80940000, 809400000, 8094000000, 80940000000, 83335786566, 809400000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Any number of the form 8094*10^j, with j>0, is part of the sequence because its Euler totient function is 2016*10^j.

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

phi(74) = 36 that is the 10's complement of the digits of 74.

MAPLE

with(numtheory): P:=proc(q) local a, b, k, n;

for n from 1 to q do a:=convert(phi(n), base, 10);

for k from 1 to nops(a) do a[k]:=(10-a[k]) mod 10; od; b:=0;

for k from 1 to nops(a) do b:=b*10+a[nops(a)-k+1]; od;

if b=n then print(n); fi; od; end: P(10^9);

PROG

(PARI) isok(x) = {my(dx = digits(x), dy = vector(#dx, k, (10-dx[k]) % 10)); fromdigits(dy) == eulerphi(x); } \\ Michel Marcus, Mar 12 2018

CROSSREFS

Cf. A000010, A055120.

Sequence in context: A250913 A186124 A204353 * A222861 A242146 A007033

Adjacent sequences:  A300484 A300485 A300486 * A300488 A300489 A300490

KEYWORD

nonn,base,more

AUTHOR

Paolo P. Lava, Mar 07 2018

EXTENSIONS

a(11)-a(15) from Giovanni Resta, Mar 09 2018

STATUS

approved

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Last modified January 26 01:48 EST 2020. Contains 331270 sequences. (Running on oeis4.)