A352535 - OEIS

%I #26 Mar 25 2022 02:57:07

%S 0,11,22,33,44,55,66,77,88,99,110,220,330,354,440,453,550,660,770,880,

%T 990,1001,1100,1111,1122,1133,1144,1155,1166,1177,1188,1199,1221,1331,

%U 1441,1487,1551,1575,1661,1771,1784,1881,1991,2002,2112,2200,2211,2222,2233,2244,2255,2266,2277

%N Numbers m such that A257588(m) = 0.

%C If m is a term, 10*m is also a term; so, terms with no trailing zeros are all primitive terms.

%C Palindromes with even number of digits (A056524) are all terms.

%F A257588(a(n)) = 0.

%e 354 is a term since 3^2 - 5^2 + 4^2 = 0 (with Pythagorean triple (3,4,5)).

%e 1487 is a term since 1^2 - 4^2 + 8^2 - 7^2 = 0.

%t f[n_] := Abs @ Total[(d = IntegerDigits[n]^2) * (-1)^Range[Length[d]]]; Select[Range[0, 2300], f[#] == 0 &] (* _Amiram Eldar_, Mar 20 2022 *)

%o (Python)

%o from itertools import count, islice

%o def A352535_gen(startvalue=0): # generator of terms >= startvalue

%o     return filter(lambda m: not sum(int(d)**2*(-1 if i % 2 else 1) for i, d in enumerate(str(m))), count(max(startvalue,0)))

%o A352535_list = list(islice(A352535_gen(),30)) # _Chai Wah Wu_, Mar 24 2022

%Y Cf. A003132, A257588.

%Y Subsequences: A056524, A333440, A338754.

%K nonn,base

%O 1,2

%A _Bernard Schott_, Mar 20 2022