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A090736 Number of positive integers <= n that can be expressed as a sum of 2 coprime squares > 0. 4
0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 7, 7, 7, 8, 8, 8, 8, 8, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 13, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 17, 18, 18, 18, 18, 18, 18, 18, 18, 19 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,5
REFERENCES
Steven R. Finch, Mathematical Constants, Cambridge, 2003, p. 100
LINKS
FORMULA
a(n) is asymptotic to (3/(8*K))*n/sqrt(log(n)) where K is the Landau-Ramanujan constant (A064533).
MATHEMATICA
Accumulate[Table[Boole[n > 1 && IntegerExponent[n, 2] < 2 && AllTrue[FactorInteger[n][[;; , 1]], Mod[#, 4] < 3 &]], {n, 1, 100}]] (* Amiram Eldar, May 08 2022 *)
PROG
(PARI) a(n)=sum(i=1, n, if(sum(u=1, i, sum(v=1, u, if(abs(u^2+v^2-i)+abs(gcd(u, v)-1), 0, 1))), 1, 0))
CROSSREFS
Sequence in context: A362344 A244479 A090735 * A094999 A280951 A120202
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 18 2004
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)