A113890 Smallest prime of the form: all eights followed by prime(n). a(n)> prime(n). 0 if no such prime exists.

0, 83, 0, 887, 811, 88813, 88817, 8819, 823, 829, 8831, 8837, 88888841, 88843, 88888888888888888888888888888847, 853, 859, 8861, 8867, 888871, 88873, 88888879, 883, 88888888888889, 88897, 8101, 888103, 8888107, 888109

Offset: 1

Author

Amarnath Murthy, Nov 18 2005

Keywords

• base
• nonn

Comments

Prime(n) is all zeros followed by prime(n). This is all eights followed by prime(n). Conjecture: a(n) is nonzero if n > 3.

Examples

			a(4) = 887, as 87 is composite, prime(4) = 7.
		

Crossrefs

Cf. A113884, A114785, A113886, A113887, A085074, A114789.

Programs

Maple

cat2 := proc(a,b) a*10^(max(1,ilog10(b)+1))+b ; end: A002282 := proc(n) 8*(10^n-1)/9 ; end: A113890 := proc(n) local p,a,n8 ; p := ithprime(n) ; for n8 from 1 to 120 do a := cat2(A002282(n8),p) ; if isprime(a) then return(a) ; fi ; od: RETURN(0) ; end: seq(A113890(n),n=1..35) ; # R. J. Mathar, Jan 31 2008

Extensions

More terms from R. J. Mathar, Jan 31 2008