cp's OEIS Frontend

A085415 Take prime[n] and continue adding 1, 2, ..., a(n) until one reaches a prime.

%I A085415 #8 Jun 12 2013 15:00:16
%S A085415 1,4,3,3,3,3,3,4,3,12,3,3,3,4,3,3,12,3,3,8,3,4,3,12,3,3,3,3,7,8,4,3,8,
%T A085415 4,12,3,3,4,3,3,12,4,3,3,8,7,7,3,3,4,3,12,4,3,3,3,12,3,3,8,4,11,3,3,8,
%U A085415 8,3,4,3,4,3,15,3,3,4,3,12,8,11,4,24,4,8,3,4,3,15,3,3,7,8,12,8,11,4,3,12,8
%N A085415 Take prime[n] and continue adding 1, 2, ..., a(n) until one reaches a prime.
%C A085415 Resulting primes in A085416. See also A085417, A085418.
%C A085415 Prime[n] plus a triangular number is prime. - _Harvey P. Dale_, Jun 12 2013
%H A085415 Harvey P. Dale, <a href="/A085415/b085415.txt">Table of n, a(n) for n = 1..1000</a>
%F A085415 Prime[n]+m*(1+m)/2 is a prime for some m>0.
%e A085415 a(2)=4 because prime[2]+(1+2+3+4)=3+10=13 is a prime
%t A085415 Flatten[(Sqrt[1+8#]-1)/2&/@With[{trnos=Accumulate[Range[30]]}, Table[ Select[ trnos,PrimeQ[Prime[n]+#]&,1],{n,100}]]] (* _Harvey P. Dale_, Jun 12 2013 *)
%Y A085415 Cf. A085416, A085417, A085418.
%K A085415 easy,nonn
%O A085415 1,2
%A A085415 _Zak Seidov_, Jun 29 2003