A244621 (First arithmetic derivative of primorials) read mod 12.

1, 5, 7, 7, 11, 5, 7, 7, 11, 1, 1, 7, 5, 5, 1, 11, 7, 1, 1, 5, 11, 11, 7, 5, 11, 1, 1, 5, 11, 1, 1, 5, 7, 7, 5, 5, 11, 11, 7, 5, 1, 7, 11, 5, 7, 7, 7, 7, 11, 5, 7, 11, 5, 1, 11, 7, 5, 5, 11, 1, 1, 11, 11, 7, 1, 11, 11, 5

Offset

1,2

Comments

A024451 as numerator of Sum_{i = 1..n} 1/prime(i) is the first arithmetic derivative of primorials prime(n)# of A002110. a(n) shows the distribution of A024451 over four residual classes.

Links

Table of n, a(n) for n=1..68.

Formula

a(n) = (prime(n)#)' mod 12 or a(n) = A024451(n) mod 12.

Example

a(4) = [(prime(4)#)' = (4#)' = (210)' = 247] mod 12 = 7,
a(6) = [(prime(6)#)' = (13#)' = (30030)' = 40361] mod 12 = 5.

Prog

(PARI) a(n) = numerator(sum(i=1, n, 1/prime(i))) % 12; \\ Michel Marcus, Jul 07 2014

Crossrefs

Cf. A002110, A024451, A003415, A244622.

Sequence in context: A264527 A137755 A258316 * A201459 A053672 A087525

Adjacent sequences: A244618 A244619 A244620 * A244622 A244623 A244624

Keyword

nonn

Author

Freimut Marschner, Jul 02 2014

Status

approved