A135618 Even Motzkin numbers divided by 2.

1, 2, 1094, 2899, 56817, 155286, 3268191, 9099642, 12834909238, 36503886401, 57494353262135, 165465534734914, 278352404864419302, 807141068080455861, 19766110689810556002, 57478249717507080819, 1418604378354657012789

Offset: 1

Author

Omar E. Pol, Feb 17 2008

Keywords

• nonn

References

• E. Deutsch and B. E. Sagan, Congruences for Catalan and Motzkin numbers and related sequences, J. Num. Theory 117 (2006), 191-215.

Crossrefs

Cf. A001006, A134718.

Programs

Mathematica

#/2&/@Select[Rest[RecurrenceTable[{a[0]==a[1]==1,a[n]==(3(n-1)a[n-2]+ (2n+1)a[n-1])/(n+2)},a,{n,60}]],EvenQ] (* Harvey P. Dale, Feb 27 2012 *)

Formula

a(n)=A134718(n)/2.