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A202237
Odd numbers with the same number of prime factors of the form 4*k+1 and 4*k+3.
2
1, 15, 35, 39, 51, 55, 87, 91, 95, 111, 115, 119, 123, 143, 155, 159, 183, 187, 203, 215, 219, 225, 235, 247, 259, 267, 287, 291, 295, 299, 303, 319, 323, 327, 335, 339, 355, 371, 391, 395, 403, 407, 411, 415, 427, 447, 451, 471, 511, 515, 519, 525, 527, 535, 543, 551
OFFSET
1,2
COMMENTS
Primes are counted with multiplicity.
Closed under multiplication.
MAPLE
isA202237 := proc(n)
if type(n, 'odd') then
A083025(n) = A065339(n) ;
else
false;
end if;
end proc:
for n from 1 to 200 do
if isA202237(n) then
printf("%d, ", n);
end if;
end do: # R. J. Mathar, Dec 16 2011
MATHEMATICA
fQ[n_]:=Plus@@((Mod[#[[1]], 4]-2)*#[[2]]&/@If[==1, {}, FactorInteger[n]]==0 && OddQ[n]; Select[Range[600], fQ] (* Ray Chandler, Dec 20 2011 *)
PROG
(PARI) netprime(n)=local(fm=factor(n)); sum(k=1, matsize(fm)[1], if(fm[k, 1]==2, 0, if(fm[k, 1]%4==1, fm[k, 2], -fm[k, 2])))
ap(n)=forstep(k=1, n, 2, if(netprime(k)==0, print1(k", ")))
CROSSREFS
A080774 (primitive elements), A072202 (even allowed).
Sequence in context: A360110 A359163 A327934 * A080774 A146319 A238605
KEYWORD
nonn
AUTHOR
STATUS
approved