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%I #28 Mar 11 2024 04:42:54
%S 0,1,4,9,16,25,36,49,64,81,1,0,-3,-8,-15,-24,-35,-48,-63,-80,4,3,0,-5,
%T -12,-21,-32,-45,-60,-77,9,8,5,0,-7,-16,-27,-40,-55,-72,16,15,12,7,0,
%U -9,-20,-33,-48,-65,25,24,21,16,9,0,-11,-24,-39,-56,36,35,32
%N If n = abcd... in decimal, a(n) = a^2 - b^2 + c^2 - d^2 + ...
%H Michel Marcus, <a href="/A257587/b257587.txt">Table of n, a(n) for n = 0..10000</a>
%F a(A352535(n)) = 0. - _Bernard Schott_, Jul 12 2022
%t A257587[n_] := Total[-(-1)^Range[Max[IntegerLength[n], 1]]*IntegerDigits[n]^2];
%t Array[A257587, 100, 0] (* _Paolo Xausa_, Mar 11 2024 *)
%o (Python)
%o def a(n): return sum(int(d)**2*(-1)**i for i, d in enumerate(str(n)))
%o print([a(n) for n in range(63)]) # _Michael S. Branicky_, Jul 11 2022
%o (PARI) a(n) = my(d=digits(n)); sum(k=1, #d, (-1)^(k+1)*d[k]^2); \\ _Michel Marcus_, Jul 12 2022
%Y First 100 terms coincide with those of A177894, but then they diverge.
%Y Cf. A257588, A257796, A352535 (indices of zeros).
%K sign,base
%O 0,3
%A _N. J. A. Sloane_, May 10 2015
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