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A136582 Sqrt(10)-primes: primes obtained by concatenating the first digits in the decimal expansion of sqrt(10). 6
3, 31, 3162277, 316227766016837933, 316227766016837933199889354443271 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
n such that floor(sqrt(10^(2*n-1))) is prime (1, 2, 7, 18, 33, ...) are given in A136583.
This sequence is the list of prime terms in A017934.
LINKS
FORMULA
a(n) = A017934(2*A136583(n)-1).
PROG
(Magma) // by Jason Kimberley, Aug 2011
for n in [1..499 by 2] do
f := Isqrt(10^n);
if IsPrime(f) then
printf "%o, ", f;
end if;
end for;
CROSSREFS
Sequence in context: A282973 A005042 A317482 * A356516 A173649 A210648
KEYWORD
nonn,base
AUTHOR
Lekraj Beedassy, Jan 09 2008
STATUS
approved

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Last modified June 8 00:26 EDT 2023. Contains 363157 sequences. (Running on oeis4.)