A227783 Stufe of Q(sqrt(-k)), where k is the n-th squarefree number.

1, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 2, 4, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 2, 4, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 4

Offset

1,2

Comments

A227782 is the main entry for this sequence.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Formula

a(n) = A227782(A005117(n)).

Prog

(PARI) apply(n->if(n%8==7, 4, if(n>1, 2, 1)), select(issquarefree, vector(200, i, i)))

Crossrefs

Cf. A227782, A227781.

Sequence in context: A367515 A122066 A053238 * A216321 A058263 A232398

Adjacent sequences: A227780 A227781 A227782 * A227784 A227785 A227786

Keyword

nonn,easy

Author

Charles R Greathouse IV, Jul 31 2013

Status

approved