click to show generating function Search the OEIS for these generating functions Search the Online Encyclopedia of Integer Sequences for the coefficients of a few of the first generating functions, in the case at hand: 1,1 1,1,2,1 1,1,2,4,3,3,1 1,1,2,4,7,7,9,10,6,4,1 1,1,2,4,7,12,14,20,26,29,26,25,20,10,5,1 1,1,2,4,7,12,20,26,38,53,68,82,89,100,101,90,71,55,35,15,6,1
O9QIM6O9QIM1O9QIM9O9QIM4O9QIMTO9QIMRO9QIMNO9QIMBO9QIMMO9QIM5O9QIMFO9QIMOO9QIMKO9QIM0O9QIMLO9QIM3O9QIMDO9QIMSO9QIMQO9QIMVO9QIMIO9QIMXO9QIMAO9QIM8O9QIMEO9QIMCO9QIM7O9QIMYO9QIMGO9QIMHO9QIM2O9QIM1