cp's OEIS Frontend

A350810 a(n) = ceiling((n-R(n^2))^2/(n+R(n^2))), where R(n^2) is the digit reversal of n^2.

%I A350810 #25 Jan 26 2022 07:23:51
%S A350810 0,1,3,50,39,48,75,27,3,8,92,407,923,651,479,606,933,372,114,11,92,
%T A350810 422,859,607,456,602,850,410,81,12,96,4106,9703,6410,5117,6814,9521,
%U A350810 4329,1139,5,1742,4547,9353,6261,5069,5976,8882,3891,904,1,919,3919,8925,6032,5041,6147,9254
%N A350810 a(n) = ceiling((n-R(n^2))^2/(n+R(n^2))), where R(n^2) is the digit reversal of n^2.
%C A350810 This sequence gives both at large and small scales well-structured graphs; specific and periodic patterns are visible in separated layers.
%H A350810 Rémy Sigrist, <a href="/A350810/b350810.txt">Table of n, a(n) for n = 1..10000</a>
%e A350810 For n = 1, R(n^2) = 1, thus a(1) = ceiling((1-1)^2/(1+1)) = 0.
%e A350810 For n = 10, R(n^2) = 1, thus a(10) = ceiling((10-1)^2/(10+1)) = 8.
%e A350810 For n = 21, R(n^2) = 144, thus a(21) = ceiling((21-144)^2/(21+144)) = 92.
%t A350810 Table[Ceiling[(n-FromDigits[Reverse[IntegerDigits[n^2]]])^2/(n+FromDigits[Reverse[IntegerDigits[n^2]]])],{n,57}] (* _Stefano Spezia_, Jan 18 2022 *)
%o A350810 (PARI) a(n) = my(x = fromdigits(Vecrev(digits(n^2))));r = ceil((n-x)^2/(n+x));
%o A350810 for(n = 1,2000,print1(a(n)", "))
%o A350810 (Python)
%o A350810 def R(n): return int(str(n)[::-1])
%o A350810 def a(n):
%o A350810     Rn2 = R(n**2)
%o A350810     q, r = divmod((n-Rn2)**2, n+Rn2)
%o A350810     return q if r == 0 else q + 1
%o A350810 print([a(n) for n in range(1, 67)]) # _Michael S. Branicky_, Jan 17 2022
%Y A350810 Cf. A000290, A002942, A004086.
%K A350810 nonn,base,easy,look
%O A350810 1,3
%A A350810 _Claude H. R. Dequatre_, Jan 17 2022