A226073 - OEIS

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A226073

Numbers k such that triangular(k)-1 is a square and triangular(k)+1 is a prime number.

%I #8 Jan 16 2023 21:41:08

%S 1,4,148,5821348,13748537282247342677718148,

%T 49900608324196518198677680899235165296598423281799348

%N Numbers k such that triangular(k)-1 is a square and triangular(k)+1 is a prime number.

%C a(7) has 191 decimal digits: 314305920...194453348.

%C Corresponding primes and roots of squares: A226072 and A226074.

%Y Cf. A226069-A226074.

%K nonn

%O 1,2

%A _Alex Ratushnyak_, May 25 2013