A198293 a(n) = (1/n)*A205406(n).

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

Author

Clark Kimberling, Jan 27 2012

Keywords

• nonn

Comments

For a guide to related sequences, see A204892.

Links

• Paolo Xausa, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A002620, A205402, A205406, A204892.

Programs

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 *)

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

Extensions

Data section extended up to a(111) by Antti Karttunen, Dec 03 2021