1,1

A(3,n) = 3rd row of semiprime power sum array A(k,n) = 1 + SUM[i=1..k]n^semiprime(i) = 1 + SUM[i=1..k]n^A001358(i). If we deem semiprime(0) = 1, the array is A(k,n) = SUM[i=0..k]n^A001358(i). This sequence a(n) is prime for n = 2, 6, 8, 20, 52. A(1,n) = first row of semiprime power sum array = 1+n^4 = A002523(n) = 10001(base n). Primes in the first row are A091940. A(2,n) = 2nd row of semiprime power sum array = A123656. A(4,n) = 4th row of semiprime power sum array is A123658. A(5,n) = 5th row of semiprime power sum array is A123659. A(6,n) = 6th row of semiprime power sum array is A123659. A(21,n) = 21st row of semiprime power sum array is A123665 whose polynomial is surprisingly reducible over Z and thus prime-free. A(n,n) = A123177 Main diagonal of semiprime power sum array.

a(n) = 1+n^4+n^6+n^9 = 1001010001 (base n).

Cf. A001358, A002523, A091940, A123177, A123656-A123665.

Sequence in context: A102201 A102204 A086143 this_sequence A069641 A079103 A169619

Adjacent sequences: A123654 A123655 A123656 this_sequence A123658 A123659 A123660

easy,nonn

Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 04 2006