Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #8 Oct 03 2019 20:59:45
%S 1,1,1,2,6,12,40,74,300,538,2598,4682,25938,47292,296488,545820,
%T 3816240,7087260,54666830,102247562,862437450,1622632496,14857095400,
%U 28091567594,277474931700,526858348368,5584100612118,10641342969902,120462266677578
%N Number of primitive (period n) periodic palindromes with integer entries that cover an initial interval of positive integers.
%H Andrew Howroyd, <a href="/A327879/b327879.txt">Table of n, a(n) for n = 0..200</a>
%F Moebius transform of A327868.
%e The a(4) = 6 primitive periodic palindromes are:
%e 1122, 1112, 1222,
%e 1213, 1232, 1323.
%o (PARI) a(n)={if(n<1, n==0, sumdiv(n, d, moebius(n/d)*sum(k=0, n, k!*(stirling((d+1)\2, k, 2)+stirling(d\2+1, k, 2))))/2)}
%Y Row sums of A327878.
%Y Cf. A327868, A327874.
%K nonn
%O 0,4
%A _Andrew Howroyd_, Sep 28 2019