A100955 -id:A100955 - cp's OEIS frontend

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

Robert G. Wilson v, Nov 23 2004

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

Cf. A100026, A100955, A100957.

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}]

A100957 Consider all (2n+1)-digit palindromic primes of the form 90...0M0...09 (so that M is a palindrome with <= 2n-1 digits); a(n) = smallest such M.

Original entry on oeis.org

1, 7, 2, 1, 2, 5, 838, 232, 121, 8, 151, 202, 2, 101, 646, 5, 1, 151, 424, 404, 242, 131, 646, 272, 16361, 1, 494, 1, 868, 101, 494, 12421, 14041, 151, 595, 383, 515, 19091, 10001, 242, 17171, 20602, 161, 292, 11011, 8, 1, 11611, 22822, 232, 17771, 616, 767

Offset: 1

Robert G. Wilson v, Nov 23 2004

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

Cf. A100026, A100955, A100956.

f[n_] := Block[{k = 0, t = Flatten[ Join[{9}, 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}]

cp's OEIS Frontend

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.

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