A114786 Smallest prime of the form: one or more 4's followed by prime(n) (or 0 if no such prime exists).

0, 43, 0, 47, 44444444444444411, 44444444413, 44417, 419, 4423, 4444444429, 431, 444444437, 4441, 443, 4447, 44453, 44444459, 461, 467, 4444471, 444473, 479, 4483, 44444489, 44497, 44101, 444444103, 444444444444107, 444109, 444113, 4127

Offset: 1

Author

Amarnath Murthy, Nov 17 2005

Keywords

• base
• nonn

Comments

Prime(n) is all 0's followed by prime(n). a(n) is all 4's followed by prime(n). Conjecture: No term is zero for n > 3.

a(346) = 0 or a(346) > 5000, but note a(892) = 3612. - D. S. McNeil, Feb 04 2011

Examples

			a(7) = 44417, as prime(7) = 17 and both 417 and 4417 are composite.
		

Crossrefs

Cf. A114783, A114784, A114785.

Programs

Mathematica

Table[If[n==1||n==3, 0, Select[FromDigits/@(Join[#,IntegerDigits[Prime[n]]]& /@ (Table[PadLeft[{4},k,4],{k,50}])),PrimeQ,1][[1]]],{n,35}]  (* Harvey P. Dale, Feb 03 2011 *)

Extensions

More terms from Joshua Zucker, May 06 2006

Edited by Jon E. Schoenfield, May 19 2019