A094666 Composite NSW numbers.

1393, 8119, 47321, 275807, 1607521, 54608393, 318281039, 1855077841, 10812186007, 367296043199, 2140758220993, 12477253282759, 72722761475561, 423859315570607, 2470433131948081, 14398739476117879, 83922003724759193

Offset

1,1

Links

Table of n, a(n) for n=1..17.

J. A. Sellers, Infinitely Many Composite NSW Numbers: An Inductive Proof

J. A. Sellers and H. Williams, On the Infinitude of Composite NSW Numbers

Mathematica

a[0] = 1; a[1] = 7; a[n_] := a[n] = 6a[n - 1] - a[n - 2]; a /@ Select[ Range[23], !PrimeQ[ a[ # ]] &] (* Robert G. Wilson v, Jun 09 2004 *)
nxt[{a_, b_}]:={b, 6b-a}; Select[NestList[nxt, {1, 7}, 30][[;; , 1]], CompositeQ] (* Harvey P. Dale, Mar 11 2023 *)

Crossrefs

Cf. A002315, A088165.

Sequence in context: A202050 A236520 A235657 * A163043 A069366 A163054

Adjacent sequences: A094663 A094664 A094665 * A094667 A094668 A094669

Keyword

nonn

Author

Lekraj Beedassy, Jun 07 2004

Extensions

More terms from Robert G. Wilson v, Jun 09 2004

Status

approved