login
First appearance of prime(n) in A157480.
0

%I #13 Aug 19 2019 17:24:19

%S 1,6,5,10,3,2,8,7,13,20,30,28,27,26,35,58,45,56,55,21,96,142,53,93,

%T 262,14,139,12,195,47,87,57,214,404,133,255,81,252,37,36,187,128,127,

%U 479,75,572,477,313,70,475,179,68,241,310,19,98,115,469,762,114,234,94,302,231,1238,229,298,376,50,161

%N First appearance of prime(n) in A157480.

%C Apparently all primes eventually appear in A157480. Note that this sequence is one-to-one map while A157480 not.

%F A157480(a(n)) = prime(n), or prime(a(n))+prime(n) is a square.

%e a(3)=5 because A157480(5)=prime(3)=5 and prime(3)+prime(5)=5+11=16=4^2,

%e a(4)=10 because A157480(10)=prime(4)=7 and prime(4)+prime(10)=7+29=36=6^2.

%Y Cf. A157480.

%K nonn

%O 1,2

%A _Zak Seidov_, Dec 10 2014