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A117458 Primes and their indices such that when their respective SOD's are both prime, the SOD of the index is the nextprime of the prime SOD. 5
227, 313, 1723, 2003, 2311, 2609, 3329, 3701, 4007, 4027, 4801, 4931, 5107, 7253, 10457, 12143, 12163, 12211, 12433, 12547, 13063, 14143, 14341, 14831, 15139, 15373, 16091, 17027, 17047, 19403, 20047, 20261, 21059, 21149, 22157, 23053, 23293, 23431, 24229, 24623 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
"SOD" = "sum of digits".
LINKS
FORMULA
Individually sum the digits of both prime index and associated prime. If both sums are prime and the sum of the index is the next prime of the prime SOD, add to sequence.
EXAMPLE
313 is a term, 65 is the index of the prime 313. The SOD(65) = 11. The SOD(313) = 7. 11 is the next prime after 7.
MATHEMATICA
Select[Range[25000], PrimeQ[#] && PrimeQ[Plus @@ IntegerDigits[#]] &&
NextPrime[Plus @@ IntegerDigits[#]] == Plus @@ IntegerDigits[PrimePi[#]] &] (* Tanya Khovanova, Mar 16 2021 *)
CROSSREFS
Sequence in context: A259059 A333425 A142261 * A252026 A210513 A142842
KEYWORD
easy,nonn,base
AUTHOR
Enoch Haga, Mar 18 2006
EXTENSIONS
Offset changed to 1 by Alois P. Heinz, Mar 16 2021
STATUS
approved

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Last modified March 28 16:58 EDT 2024. Contains 371254 sequences. (Running on oeis4.)