|
Search: id:A065439
|
|
|
| A065439 |
|
Numbers n such that s[n], p[n] and s[n]+p[n] are all prime numbers, where s[n] is the sum of digits of n and p[n] is the product of digits of n. |
|
+0
1
|
|
| 12, 21, 1112, 1121, 1211, 2111, 1111111112, 1111111121, 1111111211, 1111112111, 1111121111, 1111211111, 1112111111, 1121111111, 1211111111, 2111111111, 1111111111111112, 1111111111111121, 1111111111111211, 1111111111112111
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
p[n] will always be 2 and s[n] and s[n]+p[n] will always be twin primes.
|
|
LINKS
|
A. G. Gevisier, A curiosity about the number 12
|
|
MATHEMATICA
|
Do[s = Apply[ Plus, IntegerDigits[n]]; p = Apply[ Times, IntegerDigits[n]]; If[ PrimeQ[s] && PrimeQ[p] && PrimeQ[s + p], Print[n]], {n, 1, 10^7} ]
|
|
CROSSREFS
|
Sequence in context: A001292 A162391 A114015 this_sequence A031186 A078538 A098955
Adjacent sequences: A065436 A065437 A065438 this_sequence A065440 A065441 A065442
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Santi Spadaro (spados(AT)katamail.com), Nov 17 2001
|
|
EXTENSIONS
|
Comment and more terms from Larry Reeves (larryr(AT)acm.org), Nov 27 2001
|
|
|
Search completed in 0.002 seconds
|
