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A069636
a(1) = 9; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
9
9, 97, 197, 1973, 31973, 319733, 3319733, 331973303, 5331973303, 533197330313, 9533197330313, 953319733031321, 3953319733031321, 395331973303132171, 12395331973303132171, 1239533197330313217121, 391239533197330313217121
OFFSET
1,1
LINKS
MAPLE
A[1]:= 9:
for n from 2 to 30 do
if n::even then
for d from 1 do
x:= nextprime(A[n-1]*10^d);
if x < (A[n-1]+1)*10^d then A[n]:= x; break fi
od
else
d:=ilog10(A[n-1])+1;
for x from A[n-1]+10^d by 10^d do
if isprime(x) then A[n]:= x; break fi
od
fi
od:
seq(A[i], i=1..30); # Robert Israel, Nov 11 2020
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Amarnath Murthy, Mar 27 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Apr 03 2002
STATUS
approved