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A117738 Least number d such that 10^n -/+ 3d form a prime pair. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..55.

FORMULA

A115564(n)/3.

MATHEMATICA

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

CROSSREFS

Sequence in context: A309935 A212396 A319976 * A014582 A146142 A105854

Adjacent sequences:  A117735 A117736 A117737 * A117739 A117740 A117741

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Apr 12 2006

STATUS

approved

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Last modified December 4 14:42 EST 2020. Contains 338924 sequences. (Running on oeis4.)