first(n) = customparts(abundantsUpto(n), n)

customparts(v, n) = {
	my(res = vector(n+1)); res[1] = 1; 
	for(i = 1, #v, 
		for(j = v[i]+1, n+1,
			res[j] += res[j - v[i]]
		)
	); res
}

abundantsUpto(n) = {my(res = List());
for(i = 1, n, 
	if(sigma(i) > n<<1, 
		listput(res, i)
	)
); res
}