OFFSET
0,4
COMMENTS
Case k=3,i=3 of Gordon/Goellnitz/Andrews Theorem.
Also number of partitions in which no odd part is repeated, with at most 2 parts of size less than or equal to 2 and where differences between parts at distance 2 are greater than 1 when the larger part is odd and greater than 2 when the larger part is even.
Euler transform of period 12 sequence [1,0,1,1,0,0,0,1,1,0,1,0,...]. - Michael Somos, Jun 28 2004
REFERENCES
G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976, p. 114.
FORMULA
a(n) ~ sqrt(3 + 2*sqrt(3)) * exp(sqrt(n/3)*Pi) / (12*n^(3/4)). - Vaclav Kotesovec, May 09 2018
MATHEMATICA
a[n_] := Coefficient[ 1/Product[ 1 - ({1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0}[[Mod[k-1, 12] + 1]])*x^k, {k, 1, n}] + x*O[x]^n, x, n]; Table[a[n], {n, 0, 54}] (* Jean-François Alcover, Nov 22 2013, after Michael Somos *)
PROG
(PARI) a(n)=if(n<0, 0, polcoeff(1/prod(k=1, n, 1-([1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0][(k-1)%12+1])*x^k, 1+x*O(x^n)), n)) /* Michael Somos, Jun 28 2004 */
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Olivier Gérard, Dec 11 1999
STATUS
approved