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!)
A066874 Number of partitions of n into unitary divisors of n. 9
1, 2, 2, 2, 2, 8, 2, 2, 2, 11, 2, 12, 2, 14, 14, 2, 2, 17, 2, 17, 18, 20, 2, 20, 2, 23, 2, 22, 2, 742, 2, 2, 26, 29, 26, 27, 2, 32, 30, 29, 2, 1654, 2, 32, 32, 38, 2, 36, 2, 41, 38, 37, 2, 44, 38, 38, 42, 47, 2, 3004, 2, 50, 42, 2, 44, 5257, 2, 47, 50, 5066, 2, 47, 2, 59, 54, 52, 50 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10001 (first 329 terms by Antti Karttunen)
David A. Corneth, PARI program
EXAMPLE
a(12) = 12 because the unitary divisors of 12 are 1, 3, 4 and 12; and the partitions are 12, 4+4+4, 4+4+3+1, 4+4+(4x1), 4+3+3+1+1, 4+3+(5x1), 4+(8x1), 3+3+3+3, 3+3+3+1+1+1, 3+3+(6x1), 3+(9x1) and 12x1.
PROG
(PARI)
unitary_divisors(n) = select(d -> (1==gcd(d, n/d)), divisors(n));
partitions_into(n, parts, from=1) = if(!n, 1, my(k = #parts, s=0); for(i=from, k, if(parts[i]<=n, s += partitions_into(n-parts[i], parts, i))); (s));
A066874(n) = partitions_into(n, vecsort(unitary_divisors(n), , 4)); \\ Antti Karttunen, Aug 06 2018
(PARI) See Corneth link. \\ David A. Corneth, Aug 12 2018
CROSSREFS
Sequence in context: A337358 A295557 A327641 * A087577 A323741 A168281
KEYWORD
easy,nonn
AUTHOR
Naohiro Nomoto, Jan 26 2002
EXTENSIONS
More terms from David Wasserman, Nov 21 2002
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 March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)