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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.

A069621 a(1) = 9; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n). Alternate left and right concatenation yielding primes.

Table of values

n a(n)
1 9
2 97
3 197
4 1973
5 31973
6 319733
7 3319733
8 331973311
9 6331973311
10 633197331131
11 5633197331131
12 563319733113127
13 6563319733113127
14 65633197331131279
15 3465633197331131279
16 346563319733113127933
17 18346563319733113127933

List of values

[9, 97, 197, 1973, 31973, 319733, 3319733, 331973311, 6331973311, 633197331131, 5633197331131, 563319733113127, 6563319733113127, 65633197331131279, 3465633197331131279, 346563319733113127933, 18346563319733113127933]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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