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.

1, 2, 2, 16, 57, 325, 1666, 9787, 58979, 366329

Offset: 1

Author

V. Raman, Sep 06 2012

Keywords

• nonn
• base
• more

Examples

			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
		

Crossrefs

Cf. A000010 (phi), A115921.

Programs

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

Formula

a(n) = # { k in A115921 | 10^(n-1) < k < 10^n }. - M. F. Hasler, Feb 24 2014

Extensions

a(9)-a(10) from Amiram Eldar, May 19 2024