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A161148 Number of partitions of n such that each term of the partition is a squared divisor of n. 2
1, 1, 1, 2, 1, 2, 1, 3, 2, 3, 1, 5, 1, 4, 2, 6, 1, 9, 1, 8, 3, 6, 1, 16, 2, 7, 4, 12, 1, 21, 1, 15, 4, 9, 2, 39, 1, 10, 5, 25, 1, 35, 1, 24, 9, 12, 1, 76, 2, 21, 6, 32, 1, 61, 3, 38, 7, 15, 1, 174, 1, 16, 10, 46, 3, 93, 1, 50, 8, 42, 1, 231, 1, 19, 19, 60, 2, 135, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
FORMULA
a(p)=1 if p a prime (A000040). a(2p)=A130291(n) if p=A000040(n). a(n) = [x^n] product_{d|n} 1/( 1-x^(d^2) ).
EXAMPLE
a(n=12)=5 counts these 5 partitions of 12: 1^2+1^2+..+1^2 = 1^2+1^2+...+1^2+2^2 = 1^2+1^2+..+1^2+2^2+2^2 = 1^2+1^2+1^2+3^2=2^2+2^2+2^2. Partitions with the divisors 4, 6 or 12 do not contribute to the count because 4^2, 6^2 and 12^2 are larger than n.
MAPLE
a := proc(n) coeftayl(1/mul(1-x^(d^2), d=numtheory[divisors](n)), x=0, n) ; end:
CROSSREFS
Sequence in context: A353304 A305974 A332267 * A143773 A323524 A354713
KEYWORD
nonn
AUTHOR
R. J. Mathar, Jun 03 2009
STATUS
approved

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Last modified March 28 12:26 EDT 2024. Contains 371254 sequences. (Running on oeis4.)