A368701 a(n) = 1 if n satisfies the arithmetic differential equation 2n" - n' - 4 = 0, otherwise 0. Cf. A003415.

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

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..100023

Index entries for characteristic functions

Formula

a(n) = [0 == 2*A068346(n) - A003415(n) - 4], where [ ] is the Iverson bracket.

Prog

(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A368701(n) = (4==(2*A003415(A003415(n)) - A003415(n)));

Crossrefs

Characteristic function of A334261.

Cf. A001248, A003415, A068346.

Sequence in context: A288314 A285963 A024889 * A101349 A295308 A284954

Adjacent sequences: A368698 A368699 A368700 * A368702 A368703 A368704

Keyword

nonn

Author

Antti Karttunen, Jan 09 2024

Status

approved