A061596 Product of digits + 1 is prime, product of digits - 1 is prime, sum of digits + 1 is prime and sum of digits - 1 is prime.

4, 6, 22, 114, 123, 129, 132, 141, 156, 165, 189, 192, 198, 213, 219, 231, 237, 273, 291, 312, 321, 327, 345, 354, 372, 411, 435, 453, 459, 468, 486, 495, 516, 534, 543, 549, 561, 594, 615, 648, 651, 684, 723, 732, 819, 846, 864, 891, 912, 918, 921, 945, 954

Offset: 0

Author

Felice Russo, May 22 2001

Keywords

• base
• nonn

Examples

			22 belongs to the sequence because (2*2)+1=5, (2*2)-1=3, (2+2)+1=5, (2+2)-1=3.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..10000 (Terms 2 through 1002 from Harry J. Smith)

Crossrefs

Cf. A061595.

Programs

Mathematica

pdQ[n_]:=Module[{idn=IntegerDigits[n]},AllTrue[Flatten[{Times@@ idn+ {1,-1}, Total[idn]+{1,-1}}],PrimeQ]]; Select[Range[1000],pdQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 03 2016 *)

PARI

isok(k)={my(d=digits(k), s=vecsum(d), p=vecprod(d)); isprime(s+1) && isprime(s-1) && isprime(p+1) && isprime(p-1)} \\ Harry J. Smith, Jul 25 2009

Extensions

First two terms prepended by Harvey P. Dale, Feb 04 2016