A101155
Indices of primes in sequence defined by A(0) = 73, A(n) = 10*A(n-1) + 63 for n > 0.
Original entry on oeis.org
0, 2, 4, 5, 9, 11, 12, 38, 47, 53, 63, 81, 146, 147, 359, 398, 1637, 1875, 2145, 2193, 15788, 23073, 38465, 68399
Offset: 1
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 03 2004
7999993 is prime, hence 5 is a term.
- Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
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Select[Range[0, 100000], PrimeQ[(720*10^# - 63)/9] &] (* Robert Price, Nov 11 2015 *)
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a=73;for(n=0,1000,if(isprime(a),print1(n,","));a=10*a+63)
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for(n=0,1000,if(isprime((720*10^n-63)/9),print1(n,",")))
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
A101849
Indices of primes in sequence defined by A(0) = 37, A(n) = 10*A(n-1) + 27 for n > 0.
Original entry on oeis.org
0, 1, 13, 19, 29, 43, 65, 259, 871, 8845, 26743, 57505, 98471, 106891
Offset: 1
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 20 2004
397 is prime, hence 1 is a term.
- Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
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Select[Range[0, 1000], PrimeQ[(360*10^# - 27)/9] &] (* Robert Price, Mar 17 2015 *)
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a=37;for(n=0,1500,if(isprime(a),print1(n,","));a=10*a+27)
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for(n=0,1500,if(isprime((360*10^n-27)/9),print1(n,",")))
8845 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
A083818
Numbers k such that 2k-1 is the digit reversal of k.
Original entry on oeis.org
1, 37, 397, 3997, 39997, 399997, 3999997, 39999997, 399999997, 3999999997, 39999999997, 399999999997, 3999999999997, 39999999999997, 399999999999997, 3999999999999997, 39999999999999997, 399999999999999997, 3999999999999999997, 39999999999999999997, 399999999999999999997
Offset: 1
Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003
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