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A245010
Numbers k such that k*prime(k) + 43 is a square.
0
2, 6, 13, 57, 1614, 3686, 735417, 252641277, 4849631998, 506364553163
OFFSET
1,1
EXAMPLE
2 * 3 + 43 = 7^2;
6 * 13 + 43 = 11^2;
13 * 41 + 43 = 24^2;
57 * 269 + 43 = 124^2;
1614 * 13669 + 43 = 4697^2;
3686 * 34501 + 43 = 11277^2;
735417 * 11144513 + 43 = 2862842^2.
MATHEMATICA
Select[Range[800000], IntegerQ[Sqrt[# Prime[#]+43]]&] (* Harvey P. Dale, Aug 04 2018 *)
PROG
(Sage)
L = primes_first_n(1000000)
[n for n in [1..999999] if is_square(n*L[n-1]+43)] # Tom Edgar, Jul 10 2014
CROSSREFS
Sequence in context: A284223 A241784 A211995 * A057243 A294130 A012470
KEYWORD
nonn,more
AUTHOR
Chai Wah Wu, Jul 09 2014
EXTENSIONS
a(8)-a(10) from Giovanni Resta, Oct 14 2019
STATUS
approved