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A145992 Run lengths of 2 or more consecutive primes of the form 4k+3. 5
2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 7, 2, 2, 2, 2, 3, 2, 2, 5, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 5, 5, 2, 2, 4, 2, 2, 3, 2, 2, 3, 4, 2, 2, 3, 3, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 4, 2, 2, 3, 2, 3, 3, 2, 3, 4, 2, 2, 2, 4, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 3, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
Enoch Haga, Exploring Primes on Your PC and the Internet, 1994-2007. Pp. 30-31. ISBN 978-1-885794-24-6
LINKS
EXAMPLE
a(1) = 2 counts the two 3's from A039702(4) to A039072(5).
a(9) = 4 counts the four 3's from A039702(46) to A039072(49).
a(14)= 7 counts the seven 4's from A039702(90) to A039072(96).
MAPLE
A145992 := proc()
local m, p, r, i ;
m := 3 ;
p := 2 ;
r := 0 ;
for i from 2 to 1000 do
if modp(p, 4) = m then
r := r+1 ;
else
if r > 1 then
printf("%d, ", r) ;
end if;
r := 0;
end if;
p := nextprime(p) ;
end do:
end proc:
A145992() ; # R. J. Mathar, Aug 29 2018
MATHEMATICA
Most[Length /@ Select[ SplitBy[ Prime@ Range@ 780, Mod[#, 4] &], Mod[#[[1]], 4] == 3 && Length[#] > 1 &]] (* Giovanni Resta, Aug 29 2018 *)
Length/@Select[Split[Table[If[Mod[n, 4]==3, 1, 0], {n, Prime[Range[ 1000]]}]], FreeQ[ #, 0]&]/.(1->Nothing) (* Harvey P. Dale, Jul 27 2020 *)
CROSSREFS
Sequence in context: A277090 A103376 A189819 * A045818 A064128 A248774
KEYWORD
easy,nonn
AUTHOR
Enoch Haga, Oct 26 2008
EXTENSIONS
Corrected by R. J. Mathar, Aug 29 2018
STATUS
approved

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Last modified February 28 01:06 EST 2024. Contains 370379 sequences. (Running on oeis4.)