A245802 - OEIS

%I #33 Sep 01 2014 01:31:53

%S 1,2,3,4,5,6,7,8,14,16,21,24,28,32,35,40,42,48,49,56,64,66,70,72,75,

%T 77,84,88,90,91,98,105,112,120,126,128,129,132,133,135,140,144,145,

%U 147,150,154,161,165,168,176,180,182,192,196,198,200,203,210,216,217

%N Numbers that are divisible by the sum of their base 8 digits.

%C A base 8 version of Harshad (or Niven) numbers (A005349).

%C Numbers n such that n = 0 modulo A053829(n), where the latter sequence gives the sum of digits when n is represented in the octal number system. - _Antti Karttunen_, Aug 22 2014

%H Chai Wah Wu, <a href="/A245802/b245802.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/O#octal">Index entries for sequences related to octal numbers</a>

%e 36971 is in the sequence as it is 110153 in octal and 1 + 1 + 0 + 1 + 5 + 3 = 11 which divides 36971.

%t Select[Range[256], IntegerQ[#/(Plus@@IntegerDigits[#, 8])] &] (* _Alonso del Arte_, Aug 26 2014 *)

%o (Python)

%o from gmpy2 import digits

%o A245802 = [n for n in range(1,10**3) if not n % sum([int(d) for d in digits(n,8)])]

%o (MIT/GNU Scheme, with _Antti Karttunen_'s IntSeq-library)

%o (define A245802 (MATCHING-POS 1 1 (lambda (n) (zero? (modulo n (A053829 n))))))

%o (define (A053829 n) (let loop ((n n) (i 0)) (if (zero? n) i (loop (floor->exact (/ n 8)) (+ i (modulo n 8))))))

%Y Cf. A005349, A053829, A241989.

%K nonn,base

%O 1,2

%A _Chai Wah Wu_, Aug 22 2014