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%I #16 Apr 01 2017 20:19:40
%S 0,0,0,0,0,0,0,1,0,-1,0,2,0,-1,0,6,0,4,0,1,0,-4,0,11,0,-4,4,3,0,3,0,
%T 25,-1,-7,0,20,0,-7,-1,12,0,7,0,-2,4,-8,0,44,0,0,-2,0,0,36,0,22,-2,
%U -13,0,23,0,-12,8,90,0,0,0,-5,-2,4,0,77,0,-16,4,-3,0,4,0,55,28,-19,0,41,0,-19,-4,15,0,43,0,-2,-3,-20,0,155,0,12,5,24,0
%N a(1) = 0 and for n > 1: a(n) = A249810(n) - A078898(n) = A078898(A003961(n)) - A078898(n).
%C a(n) tells how many columns off A003961(n) is from the column where n is in square array A083221 (Cf. A083140, the sieve of Eratosthenes. The column index of n in that table is given by A078898(n)).
%H Antti Karttunen, <a href="/A249820/b249820.txt">Table of n, a(n) for n = 1..3071</a>
%F a(n) = A249810(n) - A078898(n) = A078898(A003961(n)) - A078898(n).
%F a(k) = 0 when k is a prime or square of prime, among some other numbers.
%e For n = 8 = 2*2*2, A003961(8) = 27 (3*3*3), and while 8 is on row 1 and column 4 of A083221, 27 on the next row is in column 5, thus a(8) = 5 - 4 = 1.
%e For n = 10 = 2*5, A003961(10) = 21 (3*7), and while 10 is on row 1 and column 5 of A083221, 21 on the next row is in column 4, thus a(10) = 4 - 5 = -1.
%o (Scheme) (define (A249820 n) (if (= 1 n) 0 (- (A249810 n) (A078898 n))))
%Y Cf. A003961, A078898, A083221, A083140, A246277, A249810, A249817, A249818, A249821, A249822, A251721, A251722.
%K sign
%O 1,12
%A _Antti Karttunen_, Dec 08 2014
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