A146758 Last prime subtrahend at 10^n in A146757.

7, 97, 983, 9941, 99839, 999983, 9998239, 99999989, 999950881, 9999999929, 99999999833, 999999999989, 9999999999863, 99999999999971, 999999961946087, 9999999999999917, 99999999989350667, 999999999999999989

Offset: 1

Author

Enoch Haga, Nov 02 2008

Keywords

• more
• nonn

Examples

			A(2)=97 because 97 is the 15th and last prime difference under 10^2.
		

Crossrefs

Cf. A146757, A146759, A146760.

Programs

Maple

A146758 := proc(n) local p: p:=10^n: do p:=prevprime(p): if(isprime(ceil(evalf(sqrt(p)))^2-p))then return p: fi: od: end: seq(A146758(n),n=1..14); # Nathaniel Johnston, Oct 01 2011

UBASIC

10 'sq less pr are prime 20 N=1:O=1:C=1 30 A=3:S=sqrt(N):if N>10^3 then print N,C-1:stop 40 B=N\A 50 if B*A=N then 100 60 A=A+2 70 if A<=S then 40 80 R=O^2:Q=R-N 90 if N1 print R;N;Q;C:N=N+2:C=C+1:goto 30 100 N=N+2:if N
				

Extensions

a(8)-a(18) from Nathaniel Johnston, Oct 01 2011