%I #19 Feb 27 2020 11:51:56
%S 6,10,12,14,15,18,20,22,24,26,28,30,34,35,36,38,40,42,44,45,46,48,50,
%T 52,54,56,58,60,62,63,66,68,70,72,74,75,76,77,78,80,82,84,86,88,90,91,
%U 92,94,96,98,99,100,102,104,105,106,108,110,112,114,116,117
%N Numbers which have nonpositive entries in the difference table of their divisors (complement of A273130).
%C Primorial numbers (A002110) greater than 2 are in this sequence.
%e 30 is in this sequence because the difference table of the divisors of 30 is:
%e [1, 2, 3, 5, 6, 10, 15, 30]
%e [1, 1, 2, 1, 4, 5, 15]
%e [0, 1, -1, 3, 1, 10]
%e [1, -2, 4, -2, 9]
%e [-3, 6, -6, 11]
%e [9, -12, 17]
%e [-21, 29]
%e [50]
%o (Sage)
%o def nsf(z):
%o D = divisors(z)
%o T = matrix(ZZ, len(D))
%o for m, d in enumerate(D):
%o T[0, m] = d
%o for k in range(m-1, -1, -1) :
%o T[m-k, k] = T[m-k-1, k+1] - T[m-k-1, k]
%o if T[m-k, k] <= 0: return True
%o return False
%o print([n for n in range(1, 100) if nsf(n)])
%Y Cf. A069059, A187202, A273102, A273103, A273109, A273130 (complement).
%K nonn
%O 1,1
%A _Peter Luschny_, May 16 2016