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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, 58979, 366329
OFFSET
1,2
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. A000010 (phi), A115921.
Sequence in context: A127226 A371548 A001119 * A062282 A230990 A217977
KEYWORD
nonn,base,more
AUTHOR
V. Raman, Sep 06 2012
EXTENSIONS
a(9)-a(10) from Amiram Eldar, May 19 2024
STATUS
approved