OFFSET
1,2
COMMENTS
The least integer that can be expressed as the sum of one or more consecutive numbers congruent to 1 mod 4 in exactly n ways.
Index of first occurrence of n in A333816.
LINKS
Eric Weisstein's World of Mathematics, Hexagonal Number
MATHEMATICA
nmax = 10000; A333816 = Rest[CoefficientList[Series[Sum[x^(k*(2*k - 1))/(1 - x^(4*k)), {k, 1, 1 + Sqrt[nmax/2]}], {x, 0, nmax}], x]]; Flatten[Table[FirstPosition[A333816, k], {k, 1, Max[A333816]}]] (* Vaclav Kotesovec, Apr 19 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 12 2020
EXTENSIONS
More terms from Jinyuan Wang, Apr 13 2020
STATUS
approved