A111463 a(1) = 11, then least prime beginning with the digit reversal of the previous term.

11, 113, 311, 11311, 113111, 11131111, 11113111, 1113111107, 7011113111, 111311110717, 717011113111, 111311110717, 71701111311131, 1311131111071703, 307170111131113123, 32131113111107170309, 9030717011113111312321

Offset

1,1

Links

Table of n, a(n) for n=1..17.

Example

a(3) = 311 because the reversal of a(2) = 113 is 311 and 311 is prime.
a(4) = 11311 because the reversal of a(3) = 311 is 113, which is already in the list. The next smallest prime that starts with 113 is 11311.

Maple

reverse := proc (nn) local n, m; m := 0; n := nn; while (n > 0) do m := m*10 + irem(n, 10, 'n'); od; m; end:
a := proc(n, m) option remember; global currSet; local currN, i, origN, j; if n = 0 then currSet := {m}; return m; end if; currN := reverse(a(n - 1, m)); if (not (evalb(currN in currSet))) then if (isprime(currN)) then currSet := currSet union {currN}; return currN; end if; end if; origN := currN; j := 1; while (true) do origN := 10 * origN; currN := origN; i := 0; while i < (10^j) do if (isprime(currN) and (not evalb(currN in currSet))) then currSet := currSet union {currN}; return currN; end if; currN := currN + 1; i := i + 1; end do; j := j + 1; end do; return currN; end proc; (Deugau)

Crossrefs

Cf. A090543, A111462.

Sequence in context: A090227 A050758 A166572 * A142483 A001268 A065538

Adjacent sequences: A111460 A111461 A111462 * A111464 A111465 A111466

Keyword

base,nonn

Author

Amarnath Murthy, Aug 04 2005

Extensions

More terms from Chris Deugau (deugaucj(AT)uvic.ca), Nov 04 2005

Status

approved