A110968 a(n) is the starting position of the first run of n ones in A014963.

1, 14, 20, 33, 54, 1025, 90, 513, 140, 536870913, 200, 144115188075855860, 294, 65522, 1832, 8193, 1070, 147573952589676412910, 888, 524289, 1130, 549755813889, 4178, 17179869185, 2478, 16385, 2972, 131073, 1332, 34359738338, 5592, 18014398509481952, 8468

Offset: 1

Author

Franz Vrabec, Sep 27 2005

Keywords

• nonn

Comments

Probably a(n) exists for every n in N.

If n = 2*k, then a(n) - 1 or a(n) + n is of the form 2^e. - Jinyuan Wang, Mar 21 2020

Examples

			a(3) = 20 because the first run of 3 ones in A014963 begins at position 20.
		

Links

• Franz Vrabec, Table of n, a(n) for n = 1..250

Crossrefs

Cf. A014963.

Programs

PARI

a(n) = if(n%2, my(c=0); for(k=1, oo, if(isprimepower(k), if(c==n, return(k-n), c=0), c++)), my(m=1); for(k=1, oo, m*=2; if(isprimepower(m-n-1) && sum(i=m-n, m-1, isprimepower(i))==0, return(m-n)); if(isprimepower(m+n+1) && sum(i=m+1, m+n, isprimepower(i))==0, return(m+1)))); \\ Jinyuan Wang, Mar 21 2020