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).
Original entry on oeis.org
9, 97, 197, 1973, 31973, 319733, 3319733, 331973303, 5331973303, 533197330313, 9533197330313, 953319733031321, 3953319733031321, 395331973303132171, 12395331973303132171, 1239533197330313217121, 391239533197330313217121
Offset: 1
-
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
A069629
a(1) = 2; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
Original entry on oeis.org
2, 23, 223, 2237, 32237, 3223709, 63223709, 6322370909, 66322370909, 6632237090903, 36632237090903, 3663223709090329, 73663223709090329, 736632237090903299, 5736632237090903299, 573663223709090329963
Offset: 1
A069630
a(1) = 3; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
Original entry on oeis.org
3, 31, 131, 1319, 21319, 213193, 12213193, 122131939, 1122131939, 112213193909, 17112213193909, 171122131939093, 18171122131939093, 1817112213193909339, 61817112213193909339, 618171122131939093397, 60618171122131939093397
Offset: 1
A069631
a(1) = 4; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
Original entry on oeis.org
4, 41, 241, 2411, 32411, 324113, 6324113, 63241133, 1563241133, 15632411339, 815632411339, 81563241133909, 1981563241133909, 198156324113390947, 24198156324113390947, 2419815632411339094781, 212419815632411339094781
Offset: 1
A069632
a(1) = 5; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
Original entry on oeis.org
5, 53, 353, 3533, 33533, 3353303, 123353303, 12335330333, 1112335330333, 111233533033313, 39111233533033313, 3911123353303331323, 63911123353303331323, 6391112335330333132331, 26391112335330333132331
Offset: 1
A069633
a(1) = 6; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
Original entry on oeis.org
6, 61, 461, 46103, 546103, 5461031, 55461031, 554610311, 12554610311, 125546103119, 17125546103119, 1712554610311907, 81712554610311907, 8171255461031190733, 108171255461031190733, 10817125546103119073317
Offset: 1
A069634
a(1) = 7; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
Original entry on oeis.org
7, 71, 271, 2711, 52711, 5271107, 95271107, 9527110787, 59527110787, 5952711078773, 65952711078773, 6595271107877341, 36595271107877341, 3659527110787734161, 33659527110787734161, 3365952711078773416187
Offset: 1
A069635
a(1) = 8; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).
Original entry on oeis.org
8, 83, 283, 2833, 32833, 328331, 2328331, 232833103, 31232833103, 3123283310321, 33123283310321, 3312328331032109, 333312328331032109, 33331232833103210927, 933331232833103210927, 93333123283310321092711
Offset: 1
Showing 1-8 of 8 results.