A249068 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A249068

a(n+1) gives the number of occurrences of the last digit of a(n) in octal base so far, up to and including a(n), with a(0)=0.

0, 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 1, 7, 1, 8, 2, 2, 3, 2, 4, 2, 5, 2, 6, 2, 7, 2, 8, 3, 3, 4, 3, 5, 3, 6, 3, 7, 3, 8, 4, 4, 5, 4, 6, 4, 7, 4, 8, 5, 5, 6, 5, 7, 5, 8, 6, 6, 7, 6, 8, 7, 7, 8, 8, 9, 18, 10, 11, 9, 22, 9, 24, 10, 13, 9, 28, 9, 30, 10, 14, 11, 13, 10, 15, 9, 38, 12, 11, 14, 13, 11, 15

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,4

COMMENTS

This is the octal version of Eric Angelini's A248034.

LINKS

Antti Karttunen, Table of n, a(n) for n = 0..32768

EXAMPLE

For n=16, we see that a(15) = 8, '10' in octal, and '0' has occurred just twice in the octal representations of terms a(0) .. a(15), namely in a(0) = 0 (which is also zero when read in octal base) and a(15), thus a(16) = 2.

PROG

(MIT/GNU Scheme with memoizing definec-macro from Antti Karttunen's IntSeq-library)

(definec (A249068 n) (if (zero? n) n (vector-ref (A249068aux_digit_counts (- n 1)) (modulo (A249068 (- n 1)) 8))))

(definec (A249068aux_digit_counts n) (cond ((zero? n) (vector 1 0 0 0 0 0 0 0)) (else (let loop ((digcounts-for-n (vector-copy (A249068aux_digit_counts (- n 1)))) (n (A249068 n))) (cond ((zero? n) digcounts-for-n) (else (vector-set! digcounts-for-n (modulo n 8) (+ 1 (vector-ref digcounts-for-n (modulo n 8)))) (loop digcounts-for-n (floor->exact (/ n 8)))))))))

CROSSREFS

Cf. A248034 (analogous sequence in base-10), A007094 (octal representation of n).

Sequence in context: A378359 A162520 A342703 * A308073 A090331 A338759

Adjacent sequences: A249065 A249066 A249067 * A249069 A249070 A249071

KEYWORD

nonn,base

AUTHOR

Antti Karttunen, Oct 21 2014

STATUS

approved