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A198293
a(n) = (1/n)*A205406(n).
3
1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 3
OFFSET
1,9
COMMENTS
For a guide to related sequences, see A204892.
MATHEMATICA
(See the program at A205402.)
s[m_]:=s[m]=Floor[(m+1)^2/2]/2
A205406[n_]:=(k=2; found=False; While[!found, Do[If[Mod[d=s[k]-s[j], n]==0, found=True; Break[]], {j, k-1}]; k++]; d)
nterms=100; Table[A205406[n]/n, {n, nterms}] (* Paolo Xausa, Dec 03 2021 *)
PROG
(PARI)
A002620(n) = ((n^2)>>2);
A002620shiftedleft(n) = A002620(1+n);
A205406(n) = { my(d); for(k=2, oo, for(j=1, k-1, if(!((d=A002620shiftedleft(k)-A002620shiftedleft(j))%n), return(d)))); };
A198293(n) = (A205406(n)/n); \\ Antti Karttunen, Dec 03 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 27 2012
EXTENSIONS
Data section extended up to a(111) by Antti Karttunen, Dec 03 2021
STATUS
approved