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A216387 Number of values of k for which phi(k) is a permutation of decimal digits of k, for 10^(n-1) < k < 10^n. 0
1, 2, 2, 16, 57, 325, 1666, 9787 (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 | 10^(n-1) < k < 10^n }. - M. F. Hasler, Feb 24 2014

EXAMPLE

a(3) = 2 because the values of k satisfying the condition for 10^2 < k < 10^3 are {291, 502}. - V. Raman, Feb 17 2014

PROG

(PARI) a(n)=sum(k=10^(n-1), 10^n, vecsort(digits(k)) == vecsort(digits(eulerphi(k)))) \\ V. Raman, Feb 17 2014, based on edits by M. F. Hasler

CROSSREFS

Cf. A115921, A000010.

Sequence in context: A098777 A127226 A001119 * A062282 A230990 A217977

Adjacent sequences:  A216384 A216385 A216386 * A216388 A216389 A216390

KEYWORD

nonn,base,more

AUTHOR

V. Raman, Sep 06 2012

STATUS

approved

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Last modified April 12 17:17 EDT 2021. Contains 342929 sequences. (Running on oeis4.)