|
| |
|
|
A080942
|
|
Number of divisors of n that are also suffices of n in binary representation.
|
|
8
| |
|
|
1, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 1, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 4, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,3
|
|
|
COMMENTS
| a(n)=1 iff n=2^k (A000079), the only divisor is n itself;
for a(n)>1 the other trivial divisor is 1 for odd numbers and 2 for even numbers (A057716);
a(A080943(n))=2; a(A080945(n))>2; a(A080946(n))=3; a(A080947(n))>3;
a(n) <= A000005(n); for odd primes p: a(p)=2;
a(A080948(n))=n and a(m)<n for m < A080948(n).
|
|
|
EXAMPLE
| n=63 has A000005(63)=6 divisors: 1='1', 3='11', 7='111', 9='1001', 21='10101' and 63='111111', {1,11,111,111111} are also suffices of 111111, therefore a(63)=4."
|
|
|
CROSSREFS
| Cf. A007088, A080948, A080940, A080941.
Sequence in context: A160242 A043529 A201219 * A099812 A068068 A193523
Adjacent sequences: A080939 A080940 A080941 * A080943 A080944 A080945
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 25 2003
|
| |
|
|
