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%I #24 Dec 11 2022 16:16:59
%S 1,3,21,171,1485,435,16653,149331,1342341,12076155,990528,1279200,
%T 263901,169071,446985,133865703,1180416,1214185281,2366400,25045503,
%U 247275441,8923200,19634511,56525028,229847520,739374285,224497455,81939201,24010841091,1106357280
%N First differences of A036449, triangular numbers by definition.
%H Donovan Johnson, <a href="/A189475/b189475.txt">Table of n, a(n) for n = 1..144</a>
%F a(n) = A036449(n+1) - A036449(n). [Corrected by _Georg Fischer_, Dec 11 2022]
%F A010054(a(n)) = 1.
%o (Haskell) Cf. program in A036449 (simultaneous computation).
%o (Python)
%o from itertools import count, islice
%o from sympy import integer_nthroot
%o def A189475_gen(): # generator of terms
%o a = 0
%o for n in count(1):
%o if integer_nthroot(((b:=n**2)-a<<3)+1,2)[1]:
%o yield b-a
%o a = b
%o A189475_list = list(islice(A189475_gen(),20)) # _Chai Wah Wu_, Nov 14 2022
%Y Cf. A010054, A036449.
%Y Subsequence of A000217.
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Apr 23 2011
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