A354200 - OEIS

%I #6 May 23 2022 17:45:36

%S 5,7,13,11,19,17,29,23,31,37,43,41,53,47,59,61,67,73,71,79,89,83,103,

%T 97,101,109,107,127,113,137,131,139,149,151,157,163,173,167,179,181,

%U 191,193,199,197,229,211,223,227,239,233,241,251,257,263,269,271,277,283,281,293,307,313,311,331,317,337,347,349,359

%N Prime map that sends 2 to 5, and each 4k+1 and 4k+3 prime to the next larger prime of the same type.

%F For all n >= 1, A354201(A000720(a(n))) = A000040(n).

%e A000040(2) = 3, and the next larger prime of the form 4k+3 is 7, therefore a(2) = 7.

%e A000040(3) = 5, and the next larger prime of the form 4k+1 is 13, therefore a(3) = 13.

%e A000040(4) = 7, and the next larger prime of the form 4k+3 is 11, therefore a(4) = 11.

%o (PARI) A354200(n) = if(1==n,5,my(p=prime(n), m=p%4); forprime(q=1+p,,if(m==(q%4),return(q))));

%Y Cf. A000040, A000720, A354201, A354202.

%K nonn

%O 1,1

%A _Antti Karttunen_, May 23 2022