



0, 0, 1, 0, 1, 0, 1, 0, 1, 2, 1, 0, 1, 0, 1, 2, 3, 2, 1, 2, 1, 0, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 3, 2, 3, 2, 1, 0, 1, 2, 3, 2, 3, 2, 3, 2, 1, 0, 1, 0, 1, 2, 1, 2, 3, 4, 5, 4, 3, 4, 3, 4, 3, 4, 3, 4, 3, 2, 3, 2, 3, 4, 3, 2, 1, 2, 3, 2
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,10


COMMENTS

Since this sequence equals A112632(n)1, and A007352 gives the primes at which the sign of A112632 changes, we have a change of sign in the present sequence not exactly at the primes listed in A007352, but earlier for changes to negative sign, and later for the opposite changes. Moreover, a change of sign in either of the sequences corresponds not necessarily to a change of sign (in the strict sense, i.e., regarding 0 as a number with the same sign as the preceding term) in the other one.  M. F. Hasler, Oct 09 2011


LINKS

Franklin T. AdamsWatters, Table of n, a(n) for n = 1..10000


FORMULA

a(n) = A112632(n)1.  M. F. Hasler, Oct 09 2011


MAPLE

A173950 := proc(n) if (ithprime(n)+1) mod 6 = 0 then 1; elif (ithprime(n)1) mod 6 = 0 then 1; else 0 ; end if; end proc:
A174695 := proc(n) add(A173950(i), i=1..n) ; end proc:
seq(A174695(n), n=1..90) ; # R. J. Mathar, Nov 30 2010


MATHEMATICA

Accumulate[Table[Which[Divisible[Prime[n]+1, 6], 1, Divisible[Prime[n]1, 6], 1, True, 0], {n, 150}]] (* Harvey P. Dale, Apr 24 2019 *)


PROG

(PARI) s=0; forprime(p=1, 999, print1(s+=if(p%31, p>3, 1)", ")) \\ M. F. Hasler, Oct 09 2011


CROSSREFS

Cf. A007352, A112632, A098044, A096630.
Concerning zeros or changes of sign, see also A096449 and A275939.
Sequence in context: A062756 A301574 A272728 * A165577 A259776 A318515
Adjacent sequences: A174692 A174693 A174694 * A174696 A174697 A174698


KEYWORD

sign


AUTHOR

Giovanni Teofilatto, Nov 30 2010


STATUS

approved



