A101778 Last term in each row of triangle referenced in A101777.

3, 5, 3, 2, 7, 5, 3, 7, 7, 5, 3, 2, 11, 7, 7, 5, 3, 13, 11, 7, 7, 5, 3, 2, 13, 13, 11, 7, 7, 5, 3, 17, 13, 13, 11, 7, 7, 5, 3, 2, 19, 17, 13, 13, 11, 7, 7, 5, 3, 19, 19, 17, 13, 13, 11, 7, 7, 5, 3, 2, 23, 19, 19, 17, 13, 13, 11, 7, 7, 5, 3, 23, 23, 19, 19, 17, 13, 13, 11, 7, 7, 5, 3, 2, 23

Offset

1,1

Links

Jinyuan Wang, Table of n, a(n) for n = 1..10000

Formula

a(n) = A101777(A000217(n)).

Prog

(PARI) A020482(k) = forprime(q=2, k, if(isprime(2*k-q), return(2*k-q)));
a(n) = {my(r=(ceil(sqrt(2*n+1)))^2-2*n+3); if(r%2==0, r=A020482(r/2), if(isprime(r-2), r-=2, r=A020482(r\2))); r; } \\ Jinyuan Wang, Jan 29 2020

Crossrefs

Cf. A100555, A101776, A101777.

Sequence in context: A085849 A100481 A205009 * A292570 A372801 A161670

Adjacent sequences: A101775 A101776 A101777 * A101779 A101780 A101781

Keyword

nonn

Author

Ray Chandler, Jan 10 2005

Status

approved