A353481 a(n) = 1 if n is an odd squarefree semiprime, otherwise 0.

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

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Formula

a(n) = A000035(n) * A280710(n).

a(n) = A008966(n) * A353480(n).

a(n) = A064911(n) * A323239(n).

For all n <> 4, a(n) = A353480(n) - A302048(n).

For all n >= 1, a(n) >= A353482(n) >= A353483(n).

Mathematica

Table[If[OddQ[n]&&PrimeOmega[n]==2&&SquareFreeQ[n], 1, 0], {n, 130}] (* Harvey P. Dale, Aug 17 2022 *)

Prog

(PARI) A353481(n) = ((2==bigomega(n)) && (2==omega(n)) && (1==(n%2)));

Crossrefs

Characteristic function of A046388.

Cf. A359465, A008966, A064911, A280710, A302048, A323239, A353480, A353482, A353483.

Sequence in context: A359546 A354989 A277161 * A353677 A353676 A340370

Adjacent sequences: A353478 A353479 A353480 * A353482 A353483 A353484

Keyword

nonn

Author

Antti Karttunen, Apr 22 2022

Status

approved