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A116852 Number of partitions of n-th semiprime into 2 squares. 0
1, 0, 1, 1, 0, 0, 0, 0, 2, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 2, 0, 1, 0, 1, 2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 0, 2, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 0, 0, 0, 0, 0, 1, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

COMMENTS

See also A000161 Number of partitions of n into 2 squares (when order does not matter and zero is allowed).

LINKS

Table of n, a(n) for n=1..87.

FORMULA

a(n) = A000161(A001358(n)).

EXAMPLE

a(1) = 1 because semiprime(1) = 4 = 0^2 + 2^2, the unique sum of squares.

a(2) = 0 because semiprime(2) = 6 has no decomposition into sum of 2 squares because it has a prime factor p == 3 (mod 4) with an odd power.

a(3) = 1 because semiprime(3) = 9 = 0^2 + 3^2, the unique sum of squares.

a(4) = 1 because semiprime(4) = 10 = 2*5 = 1^2 + 3^2.

a(9) = 2 because semiprime(9) = 25 = 0^2 + 5^2 = 3^2 + 4^2, two distinct ways.

a(23) = 2 because semiprime(23) = 65 = 5*13 = 1^2 + 8^2 = 4^2 + 7^2.

a(28) = 2 because semiprime(28) = 85 = 5*17 = 2^2 + 9^2 = 6^2 + 7^2.

a(49) = 2 because semiprime(49) = 145 = 5*29 = 1^2 + 12^2 = 8^2 + 9^2.

a(56) = 2 because semiprime(56) = 169 = 0^2 + 13^2 = 5^2 + 12^2.

a(60) = 2 because semiprime(60) = 185 = 5*37 = 4^2 + 13^2 = 8^2 + 11^2.

CROSSREFS

Cf. A000161, A001358.

Sequence in context: A291195 A025439 A227840 * A269245 A321886 A060154

Adjacent sequences:  A116849 A116850 A116851 * A116853 A116854 A116855

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Mar 15 2006

EXTENSIONS

More terms from Giovanni Resta, Jun 15 2016

STATUS

approved

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Last modified October 23 23:51 EDT 2019. Contains 328379 sequences. (Running on oeis4.)