A216390 Number of values of k for which sigma(k) is a permutation of decimal digits of k, for 10^(n-1) < k < 10^n.

1, 1, 5, 10, 47, 200, 842, 4698, 28831

Offset: 1

Author

V. Raman, Sep 06 2012

Keywords

• nonn
• base
• more

Examples

			a(3) = 5 because the values of k satisfying the condition for 10^2 < k < 10^3 are {258, 270, 276, 609, 639}. - _V. Raman_, Feb 18 2014
		

Crossrefs

Cf. A115920, A000203.

Programs

PARI

a(n)=sum(k=10^(n-1), 10^n, vecsort(digits(k)) == vecsort(digits(sigma(k)))) \\ V. Raman, Feb 18 2014, based on edits by M. F. Hasler

Formula

a(n) = # { k in A115920 | 10^(n-1) < k < 10^n }. - M. F. Hasler, Feb 24 2014

Extensions

a(9) from Jinyuan Wang, Mar 02 2020