1,1

This sequence appears to have only '3's and '4's. Indices of '4's seem to be given by A322408, but this is true only for n < 95: then the next term in A322408 is 95, but only a(96) = 4. - M. F. Hasler, Apr 19 2019

Table of n, a(n) for n=1..105.

(PARI) (D(v)=v[^1]-v[^-1]); A172515_vec(N)=D(A172513_upto(N*7\2)) \\ M. F. Hasler, Apr 11 2019

Cf. A172513, A167389.

Sequence in context: A329157 A082978 A005536 * A188590 A080038 A121937

Adjacent sequences: A172512 A172513 A172514 * A172516 A172517 A172518

nonn

Stephen Crowley, Feb 05 2010

Keyword "hard" removed by M. F. Hasler, Apr 11 2019

approved