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A306190 a(n) = p^2 - p - 1 where p = prime(n), the n-th prime. 2

%I

%S 1,5,19,41,109,155,271,341,505,811,929,1331,1639,1805,2161,2755,3421,

%T 3659,4421,4969,5255,6161,6805,7831,9311,10099,10505,11341,11771,

%U 12655,16001,17029,18631,19181,22051,22649,24491,26405,27721,29755,31861,32579,36289

%N a(n) = p^2 - p - 1 where p = prime(n), the n-th prime.

%C Terms are divisible by 5 iff p is of the form 10*m + 3 (A030431).

%H Robert Israel, <a href="/A306190/b306190.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A036689(n) - 1.

%F a(n) = A036690(n) - A072055(n).

%F a(n) = A060800(n) - A089241(n).

%e a(3) = 19 because 5^2 - 5 - 1 = 19.

%p map(p -> p^2-p-1, [seq(ithprime(i),i=1..100)]); # _Robert Israel_, Mar 11 2019

%t Table[Prime[n]^2-Prime[n]-1, {n, 1, 100}] (* _Jinyuan Wang_, Feb 02 2019 *)

%o (PARI) a(n) = {p=prime(n);p^2-p-1;} \\ _Jinyuan Wang_, Feb 02 2019

%Y Supersequence of A091568.

%Y Subsequence of A028387 or A165900.

%Y Cf. A000040, A030431, A036689, A036690, A060800, A072055, A089241.

%Y A039914 is an essentially identical sequence.

%K nonn

%O 1,2

%A _Kritsada Moomuang_, Jan 28 2019

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)