A342761 Fold a square sheet of paper alternately vertically to the left and horizontally downwards; after each fold, draw a line along each inward crease; after n folds, the resulting graph has a(n) edges.

4, 7, 10, 15, 25, 43, 79, 147, 283, 547, 1075, 2115, 4195, 8323, 16579, 33027, 65923, 131587, 262915, 525315, 1050115, 2099203, 4197379, 8392707, 16783363, 33562627, 67121155, 134234115, 268460035, 536903683, 1073790979

Offset

0,1

Comments

A342759 is the main sequence for this entry.

Links

Table of n, a(n) for n=0..30.

Rémy Sigrist, Illustration of initial terms

Rémy Sigrist, C# program for A342761

Formula

Theorem: a(2*t) = 2^(2*t)+3*2^(t-1)+3 for t >= 1; a(2*t+1) = 2^(2*t+1)+2^(t+1)+3 for t >= 0. - N. J. A. Sloane, Apr 26 2021

Example

See illustration in Links section.

Prog

(C#) See Links section.

Crossrefs

Cf. A342759.

It appears that a(n) = A257418(n) + 2 for n >= 2. Hugo Pfoertner, Mar 29 2021 [This is true - N. J. A. Sloane, Apr 26 2021]

Sequence in context: A071408 A137461 A137379 * A096676 A092863 A310707

Adjacent sequences: A342758 A342759 A342760 * A342762 A342763 A342764

Keyword

nonn

Author

Rémy Sigrist and N. J. A. Sloane, Mar 22 2021

Status

approved