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 A083025 Number of primes congruent to 1 modulo 4 dividing n (with multiplicity). 39
 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 2, 0, 0, 1, 0, 1, 0, 0, 1, 1, 2, 0, 0, 1, 0, 1, 0, 1, 0, 0, 2, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 2, 1, 1, 0, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,25 REFERENCES David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989, p. 61. LINKS T. D. Noe, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A001222(n) - A007814(n) - A065339(n). MAPLE A083025 := proc(n) a := 0 ; for f in ifactors(n)[2] do if op(1, f) mod 4 = 1 then a := a+op(2, f) ; end if; end do: a ; end proc: # R. J. Mathar, Dec 16 2011 MATHEMATICA f[n_]:=Plus@@Last/@Select[If[n==1, {}, FactorInteger[n]], Mod[#[[1]], 4]==1&]; Table[f[n], {n, 100}] (* Ray Chandler, Dec 18 2011 *) PROG (Haskell) a083025 1 = 0 a083025 n = length [x | x <- a027746_row n, mod x 4 == 1] -- Reinhard Zumkeller, Jan 10 2012 (PARI) A083025(n)=sum(i=1, #n=factor(n)~, if(n[1, i]%4==1, n[2, i])) \\ M. F. Hasler, Apr 16 2012 CROSSREFS First differs from A046080 at n=65. Cf. A001222, A007814, A027746, A065339 (== 3 (mod 4)). Sequence in context: A015964 A088950 A267113 * A046080 A170967 A035227 Adjacent sequences: A083022 A083023 A083024 * A083026 A083027 A083028 KEYWORD nonn,easy,nice AUTHOR Reinhard Zumkeller, Oct 29 2001 STATUS approved

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Last modified March 31 15:31 EDT 2023. Contains 361668 sequences. (Running on oeis4.)