OFFSET
2,3
COMMENTS
The length of row n is A008615(n), n >= 2.
The numerator triangle is given in A274342 where also details and references are given.
a(n) = denominator(r(n)) where the rationals r(n) are reduced to lowest terms obtained from the c(n) recurrence given in a comment of A274342 as coefficients of powers of c2 and c3 corresponding to the partitions of n with parts 2 and 3 only, when sorted with increasing number of parts.
EXAMPLE
The irregular triangle a(n, m) begins:
n\m 1 2 3
2: 1
3: 1
4: 3
5: 11
6: 13 39
7: 33
8: 2431 663
9: 247 2717
10: 8022 1989
11: 1062347 3187041
12: 16055 6605027 77571
13: 11685817 1062347
14: 2002524095 4405553009 249951
15: 497705 155409680283 11559397707
16: 1123416017295 74894401153 114727509
17: 5643476995 409716429837 10158258591
...
row n = 18: 909705199 233400836858808047 190964321066297493 18394643943,
row n = 19: 34825896536145 229850917138557 17096349208653,
row n = 20: 357856262339147 24291640943843637507 602272089516784401 174041631153.
...
For the rationals r(n), n = 2..20, see A274342.
CROSSREFS
KEYWORD
nonn,tabf,frac,easy
AUTHOR
Wolfdieter Lang, Jun 20 2016
STATUS
approved