This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
10 'recipseq, Enoch Haga, May 22 2009 20 N=3:print N:C=2 30 A=3:S=sqrt(N) 40 B=N/A 50 if A*B=int(N) then 70 60 A=A+2:if A
The 8th odd prime 23 first occurs in A145985 at index 59, so a(8) = 59.
For n=25, the 25th odd prime is 101. The first time when 10^k - 101 is a prime is when k = 12, where 10^12 - 101 = 999999999899. Furthermore, when we look at the numbers t = 10^12 - q for q an increasing prime, t is a prime for q = 11, 41, 101, ..., that is, 101 is the third success. It follows that 101 is three steps back from the end of the 12th block of descending terms in A145985. The lengths of the blocks are given by A359120. Therefore a(25) = Sum_{j=1..12} A359120(j) - (3-1) = 2528242169 - 2 = 2528242167. - _N. J. A. Sloane_, Dec 18 2022
With[{prs=Prime[Range[20000000]]},Table[Position[Select[Table[10^IntegerLength[p]-p,{p,prs}],PrimeQ],n,1,1],{n,Prime[Range[24]]}]]/.({}->-1) (* Harvey P. Dale, Dec 17 2022 *)
47 is a prime; the smallest power of 10 exceeding 47 is 100 and 100 - 47 = 53 is prime. Therefore 47 is in the sequence. 641 is a term as 641 and 1000-641 = 359 are primes.
a:=[]; for i from 1 to 1000 do p:=ithprime(i); d:=length(p); q:=10^d-p; if isprime(q) then a:=[op(a),p]; fi; od: a; # N. J. A. Sloane, Dec 18 2022
Select[Prime[Range[160]], PrimeQ[10^(Floor[Log[10, # ]] + 1) - # ] &] (* Stefan Steinerberger, Jun 15 2007 *)
is_A068811(p)= isprime(10^#Str(p)-p) & isprime(p) \\ M. F. Hasler, May 01 2012
for(d=1, 4, forprime(p=10^(d-1), 10^d, if(isprime(10^d-p), print1(p", ")))) \\ Charles R Greathouse IV, May 01 2012
[p for p in prime_range(100) if is_prime(10^p.ndigits()-p)] # Giuseppe Coppoletta, Jul 24 2016
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