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A081735 Numbers n such that the n-th Motzkin number == 1 (mod n). 2
1, 3, 4, 5, 7, 11, 13, 17, 19, 23, 25, 29, 30, 31, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 121, 127, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257 (list; graph; refs; listen; history; text; internal format)
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....

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..1000

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

Cf. A001006.

Sequence in context: A082378 A046642 A140826 * A227231 A107036 A001605

Adjacent sequences:  A081732 A081733 A081734 * A081736 A081737 A081738

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Apr 06 2003

EXTENSIONS

First term 1 prepended by Altug Alkan, Jan 07 2016

STATUS

approved

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Last modified March 21 10:13 EDT 2019. Contains 321368 sequences. (Running on oeis4.)