A071714 Numbers n such that Rd(n) + Ld(n) +/-1 is prime, where Rd and Ld are the right- and left-digital factorial functions.

2, 3, 6, 9, 33, 90, 102, 195, 210, 276, 379, 380, 402, 414, 575, 588, 616, 618, 916, 939, 980, 984, 1110, 1112, 1210, 1314, 1614, 2132, 2136, 2166, 2190, 2280, 2372, 2394, 2438, 2468, 2730, 2780, 3360, 3436, 3510, 3816, 3842, 3940, 3950, 4222, 4236, 4344

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

195 is a term because (195*95*5)+(195*19*1)+1 = 96331 and (195*95*5)+(195*19*1)-1 = 96329 are both prime.

Mathematica

rldfQ[n_]:=With[{len=IntegerLength[n]}, {a=Times@@FromDigits/@Table[Take[IntegerDigits[n], k], {k, len}]}, {b=Times@@FromDigits/@Table[Take[IntegerDigits[n], -k], {k, len}]}, AllTrue[a+b+{1, -1}, PrimeQ]]; Select[Range[5000], rldfQ] (* Harvey P. Dale, Apr 10 2026 *)

Crossrefs

Cf. A067079, A067080.

Sequence in context: A002076 A286435 A145761 * A353122 A058911 A249247

Adjacent sequences: A071711 A071712 A071713 * A071715 A071716 A071717

Keyword

base,nonn

Author

Jason Earls, Jun 03 2002

Status

approved