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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064438 Numbers which are divisible by the sum of their quaternary digits. 22
1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 20, 21, 24, 28, 30, 32, 33, 35, 36, 40, 42, 48, 50, 52, 54, 60, 63, 64, 66, 68, 69, 72, 76, 78, 80, 81, 84, 88, 90, 91, 96, 100, 102, 108, 112, 114, 120, 126, 128, 129, 132, 136, 138, 140, 144, 148, 150, 154, 156, 160, 162, 168, 171, 180 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
A good "puzzle" sequence -- guess the rule given the first twenty or so terms.
LINKS
Paul Dalenberg and Tom Edgar, Consecutive factorial base Niven numbers, Fibonacci Quart. (2018) Vol. 56, No. 2, 163-166.
EXAMPLE
Quaternary representation of 28 is 130, 1 + 3 + 0 = 4 divides 28.
MATHEMATICA
Select[Range[200], Divisible[#, Total[IntegerDigits[#, 4]]]&] (* Harvey P. Dale, Jun 09 2011 *)
PROG
(ARIBAS): maxarg := 190; for n := 1 to maxarg do if n mod sum(quaternarray(n)) = 0 then write(n, " "); end; end; function quaternarray(n: integer): array; var k: integer; stk: stack; begin while n > 0 do k := n mod 4; stack_push(stk, k); n := (n - k) div 4; end; return stack2array(stk); end; .
(PARI)
SumD(x)= { local(s); s=0; while (x>9, s+=x-10*(x\10); x\=10); return(s + x) }
baseE(x, b)= { local(d, e, f); e=0; f=1; while (x>0, d=x-b*(x\b); x\=b; e+=d*f; f*=10); return(e) }
{ n=0; for (m=1, 10^9, if (m%(SumD(baseE(m, 4)))==0, write("b064438.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 14 2009
(PARI) isok(n) = !(n % sumdigits(n, 4)); \\ Michel Marcus, Jun 24 2018
(Python)
from sympy.ntheory.factor_ import digits
print([n for n in range(1, 201) if n%sum(digits(n, 4)[1:]) == 0]) # Indranil Ghosh, Apr 24 2017
CROSSREFS
Cf. A005349 (decimal), A049445 (binary), A064150 (ternary).
Sequence in context: A048716 A010434 A074230 * A227731 A067947 A279542
KEYWORD
base,easy,nice,nonn
AUTHOR
Len Smiley, Oct 01 2001
EXTENSIONS
More terms from Matthew Conroy, Oct 02 2001
Offset changed from 0 to 1 by Harry J. Smith, Sep 14 2009
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 24 09:09 EDT 2024. Contains 374575 sequences. (Running on oeis4.)