A101960 Indices of primes in sequence defined by A(0) = 29, A(n) = 10*A(n-1) - 41 for n > 0.

0, 14, 30, 72, 96, 498, 4206, 5901, 9567, 12141, 13047, 38340, 80166, 91902

Offset

1,2

Comments

Numbers n such that (220*10^n + 41)/9 is prime.

Numbers n such that digit 2 followed by n >= 0 occurrences of digit 4 followed by digit 9 is prime.

Numbers corresponding to terms <= 498 are certified primes.

a(15) > 10^5. - Robert Price, Feb 05 2015

References

Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.

Links

Table of n, a(n) for n=1..14.

Makoto Kamada, Prime numbers of the form 244...449.

Index entries for primes involving repunits.

Formula

a(n) = A102955(n) - 1.

Example

29 is prime, hence 0 is a term.

Prog

(PARI) a=29; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-41)
(PARI) for(n=0, 1500, if(isprime((220*10^n+41)/9), print1(n, ", ")))

Crossrefs

Cf. A000533, A002275, A102955.

Sequence in context: A027575 A104776 A308312 * A075208 A228124 A293391

Adjacent sequences: A101957 A101958 A101959 * A101961 A101962 A101963

Keyword

nonn,hard,more

Author

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 23 2004

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

a(10)-a(14) from Robert Price, Feb 05 2015

Status

approved