%I #16 Sep 12 2019 15:01:08
%S 1,2,4,9,20,50,147,269,992,1000,4297,76468,97314,445519,1315337,
%T 2594742,3888902,91859035,92411466,1180624310,4501485474,11288114818,
%U 23434425843
%N Records in A171868 (positions).
%H Rémy Sigrist, <a href="/A171887/a171887.txt">C program for A171887</a>
%o (Python)
%o A181391_list, A171887_list, l, r, k = [0, 0], [1], 0, 1, 1
%o for n in range(1, 10**6):
%o ....for m in range(n-1, -1, -1):
%o ........if A181391_list[m] == A181391_list[n]:
%o ............A181391_list.append(n-m)
%o ............break
%o ....else:
%o ........A181391_list.append(0)
%o ........k += 1
%o ........if n-l > r:
%o ............r = n-l
%o ............A171887_list.append(k)
%o ........l = n # _Chai Wah Wu_, Jan 02 2015
%o (C) See Links section.
%Y Cf. A181391, A171865, A171868, A171888.
%K nonn,more
%O 1,2
%A _N. J. A. Sloane_, Oct 18 2010
%E a(12)-a(13) from _Chai Wah Wu_, Jan 02 2015
%E a(14)-a(17) from _Rémy Sigrist_, Jun 11 2019
%E a(18)-a(23) from _Benjamin Chaffin_, Sep 11 2019