A117738 Least number d such that 10^n -/+ 3d form a prime pair.

1, 1, 3, 23, 43, 13, 87, 71, 153, 11, 19, 13, 89, 219, 119, 459, 1, 129, 633, 131, 71, 217, 1091, 911, 1141, 511, 143, 201, 377, 379, 371, 377, 83, 201, 993, 53, 143, 307, 423, 919, 259, 263, 759, 3933, 3, 1781, 607, 2327, 7683, 541, 3443, 6507, 4023, 3399, 899

Offset: 1

Author

Robert G. Wilson v, Apr 12 2006

Keywords

• nonn

Programs

Mathematica

f[n_] := Block[{k = 1}, While[ ! PrimeQ[10^n - 3k] || ! PrimeQ[10^n + 3k], k++ ]; k]; Array[f, 55]

Formula

A115564(n)/3.