cp's OEIS Frontend

A263087 a(n) = A060990(n^2); number of solutions to x - d(x) = n^2, where d(x) is the number of divisors of x (A000005).

%I A263087 #14 Nov 08 2015 04:47:20
%S A263087 2,2,1,1,1,0,0,0,0,2,0,1,2,1,0,1,0,1,0,1,0,2,0,1,2,1,0,0,0,1,1,2,1,1,
%T A263087 0,0,2,0,1,1,1,1,1,1,1,1,0,0,2,1,0,1,1,1,0,1,0,1,0,0,0,1,0,1,1,1,1,0,
%U A263087 1,1,1,2,3,0,1,1,1,1,0,1,1,1,0,1,1,0
%N A263087 a(n) = A060990(n^2); number of solutions to x - d(x) = n^2, where d(x) is the number of divisors of x (A000005).
%H A263087 Antti Karttunen, <a href="/A263087/b263087.txt">Table of n, a(n) for n = 0..10082</a>
%F A263087 a(n) = A060990(n^2) = A060990(A000290(n)).
%o A263087 (PARI)
%o A263087 A060990(n) = { my(k = n + 2400, s=0); while(k > n, if(((k-numdiv(k)) == n),s++); k--;); s}; \\ Hard limit A002183(77)=2400 good for at least up to A002182(77) = 10475665200.
%o A263087 A263087(n) = A060990(n^2);
%o A263087 for(n=0, 10082, write("b263087.txt", n, " ", A263087(n)));
%o A263087 (Scheme) (define (A263087 n) (A060990 (A000290 n)))
%Y A263087 Cf. A000005, A000290, A002182, A002183, A060990.
%Y A263087 Cf. A263093 (positions of zeros), A263092 (nonzeros).
%Y A263087 Cf. A263250, A263251 (bisections) and A263252, A263253 (their partial sums).
%Y A263087 Cf. also A261088, A263088.
%K A263087 nonn
%O A263087 0,1
%A A263087 _Antti Karttunen_, Oct 12 2015