login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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. 0
1, 1, 5, 10, 47, 200, 842, 4698, 28831 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..9.

FORMULA

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

EXAMPLE

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

PROG

(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

CROSSREFS

Cf. A115920, A000203.

Sequence in context: A035406 A103932 A034190 * A305476 A270089 A336582

Adjacent sequences:  A216387 A216388 A216389 * A216391 A216392 A216393

KEYWORD

nonn,base,more

AUTHOR

V. Raman, Sep 06 2012

EXTENSIONS

a(9) from Jinyuan Wang, Mar 02 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 30 03:03 EDT 2020. Contains 337432 sequences. (Running on oeis4.)