A071374 0 iff n is of the form 4^a*(8k+7), otherwise 1.

1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1

Offset

0,1

Comments

0 iff n is not the sum of three squares.

Links

Table of n, a(n) for n=0..98.

Jean-Paul Allouche and Jeffrey Shallit, The ring of k-regular sequences, preprint.

Jean-Paul Allouche and Jeffrey Shallit, The ring of k-regular sequences, Theoretical Computer Sci., Vol. 98 (1992), pp. 163-197.

Index entries for 2-automatic sequences.

Formula

From Amiram Eldar, May 15 2025: (Start)

a(n) = 1 - A072401(n);

Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 5/6. (End)

Prog

(PARI) a(n) = if(n, (n >> (2*valuation(n, 4))) % 8 < 7, 1); \\ Amiram Eldar, May 15 2025

Crossrefs

1's complement to A072401. Cf. A071377.

Sequence in context: A212793 A307420 A129667 * A071025 A077010 A330548

Adjacent sequences: A071371 A071372 A071373 * A071375 A071376 A071377

Keyword

nonn,easy

Author

N. J. A. Sloane, Jun 12 2002

Status

approved