login
A034794
a(n) is the least prime p > a(n-1) such that a(n-1) is a quadratic residue mod p.
5
2, 7, 19, 31, 41, 43, 53, 59, 67, 73, 79, 89, 97, 101, 107, 127, 139, 151, 163, 173, 179, 193, 197, 223, 241, 251, 283, 293, 307, 313, 317, 353, 383, 389, 409, 419, 443, 457, 461, 467, 487, 499, 521, 523, 571, 577, 593, 601, 607, 619, 631, 641, 643, 653, 659
OFFSET
1,1
COMMENTS
a(n-1) is a term in row a(n) of A046071. - Reinhard Zumkeller, May 10 2015
MAPLE
f:= proc(t) local i, p;
p:= t;
do
p:= nextprime(p);
if numtheory:-jacobi(t, p) = 1 then return p fi
od
end proc:
A[1]:= 2:
for n from 2 to 100 do A[n]:= f(A[n-1]) od:
seq(A[i], i=1..100); # Robert Israel, Sep 04 2016
MATHEMATICA
f[n_] := Block[{k = PrimePi[n] + 1}, While[ JacobiSymbol[n, Prime[k]] == -1, k++ ]; Prime[k]]; NestList[f, 2, 54] (* Robert G. Wilson v, Mar 16 2004 *)
PROG
(Haskell)
a034794 n = a034794_list !! (n-1)
a034794_list = 2 : f 2 (tail a000040_list) where
f x (p:ps) = if elem x $ a046071_row p then p : f p ps else f x ps
-- Reinhard Zumkeller, May 10 2015
CROSSREFS
Cf. A092581.
Sequence in context: A144589 A179002 A232667 * A213892 A152608 A334520
KEYWORD
nonn,nice
EXTENSIONS
Mathematica updated by Jean-François Alcover, Jul 04 2013
Name corrected by Robert Israel, Sep 04 2016
STATUS
approved