Number of triangular involutions of n. A triangular involution is a square involution with at most three faces.

A164991

Number of triangular involutions of n. A triangular involution is a square involution with at most three faces.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =6a(4) =13a(5) =26a(6) =54a(7) =108a(8) =221a(9) =442a(10) =898a(11) =1796a(12) =3634a(13) =7268a(14) =14668a(15) =29336a(16) =59101a(17) =118202a(18) =237834a(19) =475668a(20) =956198a(21) =1912396a(22) =3841588a(23) =7683176a(24) =15425138a(25) =30850276a(26) =61908564a(27) =123817128a(28) =248377156a(29) =496754312

External references