0,2

The all-1 entries occur at positions indexed by the n-th primes-2 (A040976). The 1's then sum to give n-th prime-1 (A006093). Rows of A003989 expressed as base 10 numbers. The sum of the digits of a(n) are given by A006579(n+1).

a(n)=sum{k=0..n, gcd(n-k+1, k+1)10^k}

Sequence in context: A073913 A080445 A033867 this_sequence A125315 A132583 A007907

Adjacent sequences: A106470 A106471 A106472 this_sequence A106474 A106475 A106476

easy,nonn

Paul Barry (pbarry(AT)wit.ie), May 03 2005