OFFSET
1,2
COMMENTS
All odd primes and all squares of primes are in the sequence. First composite (and not square of prime) are : 30, 464, 902, 21475, ... (A081736). [Scott R. Shannon points out that this comment is wrong, since 9 is missing. Are there other errors? The comment needs to checked and corrected. - N. J. A. Sloane, Dec 15 2022]
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..1000
MATHEMATICA
motzkin[0] = 1; motzkin[n_] := motzkin[n] = motzkin[n - 1] + Sum[motzkin[k] * motzkin[n - k - 2], {k, 0, n - 2}]; Select[Range[250], # == 1 || Mod[motzkin[#], #] == 1 &] (* Amiram Eldar, May 23 2022 *)
PROG
(PARI) a001006(n) = polcoeff((1-x-sqrt((1-x)^2-4*x^2+x^3*O(x^n)))/(2*x^2), n);
for(n=1, 1e3, if((a001006(n)-1) % n == 0, print1(n, ", "))); \\ Altug Alkan, Jan 07 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Apr 06 2003
EXTENSIONS
First term 1 prepended by Altug Alkan, Jan 07 2016
STATUS
approved