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A369629 Number of solutions to +- 1^4 +- 2^4 +- 3^4 +- ... +- n^4 = 0 or 1.

%I A369629 #16 Jan 30 2024 01:29:03
%S A369629 1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,5,0,16,18,0,21,32,100,126,0,424,
%T A369629 510,0,1428,2792,5988,9786,7,29058,45106,22,150437,276828,473854,
%U A369629 836737,1838,2455340,4777436,15847,14696425,27466324,46429640,83010230,738627
%N A369629 Number of solutions to +- 1^4 +- 2^4 +- 3^4 +- ... +- n^4 = 0 or 1.
%H A369629 Chai Wah Wu, <a href="/A369629/b369629.txt">Table of n, a(n) for n = 0..73</a>
%o A369629 (Python)
%o A369629 from itertools import count, islice
%o A369629 from collections import Counter
%o A369629 def A369629_gen(): # generator of terms
%o A369629     ccount = Counter({0:1})
%o A369629     yield 1
%o A369629     for i in count(1):
%o A369629         bcount = Counter()
%o A369629         for a in ccount:
%o A369629             bcount[a+(j:=i**4)] += ccount[a]
%o A369629             bcount[a-j] += ccount[a]
%o A369629         ccount = bcount
%o A369629         yield(ccount[0]+ccount[1])
%o A369629 A369629_list = list(islice(A369629_gen(),20)) # _Chai Wah Wu_, Jan 29 2024
%Y A369629 Cf. A000583, A025591, A111253, A158465, A350403, A350861.
%K A369629 nonn
%O A369629 0,17
%A A369629 _Ilya Gutkovskiy_, Jan 28 2024
%E A369629 a(46)-a(50) from _Chai Wah Wu_, Jan 29 2024