A100956 Consider all (2n+1)-digit palindromic primes of the form 70...0M0...07 (so that M is a palindrome with <= 2n-1 digits); a(n) = smallest such M.

2, 2, 141, 2, 545, 5, 141, 282, 111, 3, 141, 5, 131, 282, 141, 141, 9, 3, 2, 303, 171, 6, 222, 323, 2, 393, 797, 606, 191, 404, 414, 363, 797, 171, 474, 737, 25752, 545, 20502, 14241, 848, 12821, 15951, 474, 575, 12321, 2, 17771, 8, 666, 14541, 15651, 171, 191

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Mathematica

f[n_] := Block[{k = 0, t = Flatten[ Join[{7}, Table[0, {n - 1}]]]}, While[s = Drop[t, Min[ -Floor[ Log[10, k]/2], 0]]; k != FromDigits[ Reverse[ IntegerDigits[k]]] || !PrimeQ[ FromDigits[ Join[s, IntegerDigits[k], Reverse[s]]]], k++ ]; k]; Table[ f[n], {n, 55}]

Crossrefs

Cf. A100026, A100955, A100957.

Sequence in context: A376440 A003110 A395697 * A358621 A383654 A304915

Adjacent sequences: A100953 A100954 A100955 * A100957 A100958 A100959

Keyword

base,nonn

Author

Robert G. Wilson v, Nov 23 2004

Status

approved