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 A230665 Primes which are equal to the digit sum of 38^n, in the order that they are found. 1
 11, 13, 41, 37, 47, 67, 53, 79, 59, 109, 107, 109, 139, 151, 167, 173, 229, 263, 271, 307, 397, 389, 409, 421, 383, 463, 439, 419, 487, 467, 491, 569, 599, 647, 653, 613, 677, 683, 757, 751, 727, 853, 821, 881, 907, 937, 1021, 1061, 1033, 1087, 1193, 1249, 1229 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The expression k^n with 1 < n < 100 generates more primes with k=38 than any other value of k in the range 1 < k < 100. Hence, 38 is considered for this sequence such that digit sum of 38^n is prime. 38 generates 37 primes in that range of k. The 404 is the next better prime generator, with 40 primes. Next two records are 278249 with 43 primes and 458635073 with 45. (No more records to 10^9.) - Charles R Greathouse IV, Jan 21 2014 LINKS K. D. Bajpai, Table of n, a(n) for n = 1..4000 EXAMPLE a(3)= 41: 38^5= 79235168: The digital sum= 7+9+2+3+5+1+6+8= 41 which is prime. a(6)= 67: 38^8= 4347792138496: The digital sum= 4+3+4+7+7+9+2+1+3+8+4+9+6= 67 which is prime. MAPLE with(StringTools):KD := proc() local a, b; a:= 38^n ; b:=add( i, i = convert((a), base, 10))(a); if isprime(b) then return (b); fi; end: seq(KD(), n=1..500); MATHEMATICA Select[Table[Total[IntegerDigits[38^k]], {k, 100}], PrimeQ] PROG (PARI) list(maxx)={cnt=0; q=38; new=1; n=1; while(n

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Last modified May 19 00:35 EDT 2024. Contains 372666 sequences. (Running on oeis4.)