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A216385 Number of values of k for which phi(k) is a permutation of decimal digits of k, for k < 10^n. 0
1, 3, 5, 21, 78, 403, 2069, 11856 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..8.

FORMULA

a(n) = # { k in A115921 | k < 10^n }. - M. F. Hasler, Feb 24 2014

EXAMPLE

a(3) = 5 because the values of k satisfying the condition for k < 10^3 are {1, 21, 63, 291, 502}. - V. Raman, Feb 17 2014

PROG

(PARI) a(n)=sum(k=1, 10^n, vecsort(digits(k)) == vecsort(digits(eulerphi(k)))) \\ Use digits(n)=eval(Vec(Str(n))) in old versions of PARI. - V. Raman, Feb 17 2014, based on edits by M. F. Hasler

CROSSREFS

Cf. A115921, A000010.

Sequence in context: A071706 A196418 A189560 * A247680 A179265 A084253

Adjacent sequences:  A216382 A216383 A216384 * A216386 A216387 A216388

KEYWORD

nonn,base,more

AUTHOR

V. Raman, Sep 06 2012

STATUS

approved

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Last modified July 19 08:23 EDT 2019. Contains 325155 sequences. (Running on oeis4.)