cp's OEIS Frontend

A048208 a(n) = T(2n-1,n), array T given by A048201.

%I A048208 #17 Sep 02 2025 18:16:12
%S A048208 1,6,17,37,63,98,139,186,240,298,359,431,505,589,683,779,892,1018,
%T A048208 1150,1288,1431,1593,1762,1949,2151,2366,2591,2823,3061,3304,3557,
%U A048208 3820,4095,4367,4645,4930,5222,5530,5851,6176,6517,6868,7222,7582,7952,8331,8710
%N A048208 a(n) = T(2n-1,n), array T given by A048201.
%H A048208 Chai Wah Wu, <a href="/A048208/b048208.txt">Table of n, a(n) for n = 1..10000</a>
%F A048208 a(n) = A004978(2*n) - A004978(n). - _Sean A. Irvine_, Jun 05 2021
%o A048208 (Python)
%o A048208 from itertools import count, accumulate, islice
%o A048208 from collections import deque
%o A048208 def A048208_gen(): # generator of terms
%o A048208     aset, alist, b, blist, c = set(), deque(), 1, [], 0
%o A048208     for k in count(1):
%o A048208         if k in aset:
%o A048208             aset.remove(k)
%o A048208         else:
%o A048208             if c&1:
%o A048208                 yield b-blist[c>>1]
%o A048208             aset |= set(k+d for d in accumulate(alist))
%o A048208             alist.appendleft(k)
%o A048208             blist.append(b)
%o A048208             b += k
%o A048208             c += 1
%o A048208 A048208_list = list(islice(A048208_gen(),47)) # _Chai Wah Wu_, Sep 02 2025
%Y A048208 Cf. A004978, A048201.
%K A048208 nonn,changed
%O A048208 1,2
%A A048208 _Clark Kimberling_
%E A048208 More terms from _Sean A. Irvine_, Jun 05 2021