1,1

A143201(a(n)) = 5;

A020639(a(n))in A023200 and A006530(a(n)) in A046132;

subsequence of A007774: A001221(a(n))=2.

Eric Weisstein's World of Mathematics, Cousin Primes

Index entries for primes, gaps between

a(1) = 21 = 3 * 7 = A023200(1) * A046132(1);

a(2) = 63 = 3^2 * 7 = A023200(1)^2 * A046132(1);

a(3) = 77 = 7 * 11 = A023200(2) * A046132(2);

a(4) = 147 = 3 * 7^2 = A023200(1) * A046132(1)^2;

a(5) = 189 = 3*3 * 7 = A023200(1)^3 * A046132(1);

a(6) = 221 = 13 * 17 = A023200(3) * A046132(3);

a(7) = 437 = 19 * 23 = A023200(4) * A046132(4);

a(8) = 441 = 3^2 * 7^2 = A023200(1)^2 * A046132(1)^2;

a(9) = 539 = 7^2 * 11 = A023200(2)^2 * A046132(2);

a(10) = 567 = 3^4 * 7 = A023200(1)^4 * A046132(1).

Sequence in context: A126375 A081302 A058100 this_sequence A082060 A025525 A033850

Adjacent sequences: A143200 A143201 A143202 this_sequence A143204 A143205 A143206

nonn

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 12 2008