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A089699 Numbers n with property that n + 1 as well as the (product of digits of n) + 1 are primes. 3
1, 2, 4, 6, 12, 16, 22, 28, 36, 52, 58, 66, 82, 112, 126, 136, 156, 162, 166, 192, 198, 232, 256, 268, 292, 312, 316, 346, 348, 352, 366, 372, 388, 396, 438, 486, 556, 562, 568, 576, 586, 612, 616, 652, 658, 682, 732, 756, 768, 786, 796, 826, 838, 856, 862 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MAPLE
for n from 1 to 150 do p:=ithprime(n): m:=mul(j, j=convert(p-1, base, 10)): if isprime(m+1) then printf("%d, ", p-1) fi od: # C. Ronaldo
MATHEMATICA
Select[Prime[Range[200]]-1, PrimeQ[Times@@IntegerDigits[#]+1]&] (* Harvey P. Dale, Apr 09 2014 *)
CROSSREFS
Sequence in context: A188047 A032465 A089395 * A089696 A171609 A099316
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 10 2003
EXTENSIONS
Corrected and extended by C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004
STATUS
approved

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Last modified June 20 18:36 EDT 2024. Contains 373532 sequences. (Running on oeis4.)