1,3

Triangle A054521 * A000005 as a vector; where 1's indicate the relative primes of n by rows and A000005 = d(n): (1, 2, 2, 3, 2, 4, 2, 4, 3,...)

a(8) = 7 since the relative primes of 8 are (1, 3, 5, 7). (d(1) + d(3) + d(5) + d(7)) = 1 + 2 + 2 + 2). Or, a(8) = 7 = (1, 0, 1, 0, 1, 0, 1, 0) dot (1, 2, 2, 3, 2, 4, 2, 4), where (1, 0, 1, 0, 1, 0, 1, 0) = row 8 of triangle A054521 and d(n) = (1, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2,...).

a(7) = 14 = (1, 1, 1, 1, 1, 1, 0) dot (1, 2, 2, 3, 2, 4, 2) = (d(1) + d(2) + d(3) + d(4) + d(5) + d(6)).

Cf. A054521, A000005, A143614.

Sequence in context: A164040 A154178 A029614 this_sequence A016606 A069462 A097469

Adjacent sequences: A143612 A143613 A143614 this_sequence A143616 A143617 A143618

nonn

Gary W. Adamson (qntmpkt(AT)yahoo.com), Aug 27 2008