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 A039996 Primes embedded in prime(n) as substrings. 72
 1, 1, 1, 1, 1, 2, 2, 1, 3, 2, 2, 3, 1, 2, 2, 3, 2, 1, 2, 2, 3, 2, 2, 1, 2, 1, 2, 2, 1, 4, 3, 4, 5, 3, 1, 2, 3, 2, 3, 5, 4, 1, 2, 3, 4, 2, 3, 4, 3, 3, 4, 4, 3, 3, 4, 3, 2, 4, 3, 2, 4, 4, 3, 4, 4, 5, 3, 4, 4, 2, 4, 4, 4, 5, 5, 3, 3, 4, 1, 1, 3, 2, 4, 3, 3, 3, 1, 3, 2, 2, 3, 4, 2, 1, 1, 3, 2, 3, 5, 3, 4, 3, 3, 2, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS FORMULA a(n) = A039997(prime(n)). a(n) <= A039994(n). - Charles R Greathouse IV, Apr 22 2015 EXAMPLE a(26) = 1 since the only prime substring of "101" is 101. MATHEMATICA f[n_] := Block[{id = IntegerDigits@ Prime@n, len = Floor[ Log[10, Prime@n] + 1]}, Count[ PrimeQ@ Union[ FromDigits@# & /@ Flatten[ Table[ Partition[id, k, 1], {k, len}], 1]], True]]; Array[f, 105] (* Robert G. Wilson v, Jun 28 2010 *) PROG (PARI) dp(n)=if(n<12, return(if(isprime(n), [n], []))); my(v=vecsort(select(isprime, eval(Vec(Str(n)))), , 8), t); while(n>9, if(gcd(n%10, 10)>1, n\=10; next); t=10; while((t*=10)

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Last modified April 18 12:34 EDT 2019. Contains 322209 sequences. (Running on oeis4.)