A224846 Smallest k such that (10^n+k, 10^n+k+2) and (10^(n+1)+k, 10^(n+1)+k+2) are two pairs of twin primes with k(n+1) > k(n).

1, 49, 91, 1117, 2929, 3001, 4831, 37237, 43897, 54409, 55669, 81931, 89809, 194971, 271159, 556651, 628069, 639247, 1036447, 1615597, 2075407, 2086447, 2414077, 3331009, 3442789, 4088539, 4178311, 4330681, 5834869, 6846649, 7928047, 11222341, 15520927, 18575911, 18615787, 22426969, 22645189

Offset

1,2

Links

Pierre CAMI, Table of n, a(n) for n = 1..75

Example

10^1+1=11 prime as 13 10^2+1=101 prime as 103 so a(1)=1.

Mathematica

i = -1; Table[i = i + 2; While[! (PrimeQ[10^n + i] && PrimeQ[10^n + i + 2] && PrimeQ[10^(n + 1) + i] && PrimeQ[10^(n + 1) + i + 2]), i = i + 2]; i, {n, 10}] (* T. D. Noe, Jul 23 2013 *)

Prog

PFGW & SCRIPTIFY
SCRIPT
DIM n, 0
DIM k, -1
DIMS t
OPENFILEOUT myf, a(n).txt
LABEL a
SET n, n+1
LABEL b
SET k, k+2
SETS t, %d, %d\,; n; k
PRP 10^n+k, t
IF ISPRP THEN GOTO c
GOTO b
LABEL c
PRP 10^n+k+2, t
IF ISPRP THEN GOTO d
GOTO b
LABEL d
PRP 10^(n+1)+k, t
IF ISPRP THEN GOTO e
GOTO b
LABEL e
PRP 10^(n+1)+k+2, t
IF ISPRP THEN GOTO f
GOTO b
LABEL f
WRITE myf, t
SET k, k+2
GOTO a

Crossrefs

Cf. A124001 (10^n+k and 10^n+k+2 are prime).

Sequence in context: A020176 A146064 A224905 * A260469 A275419 A031180

Adjacent sequences: A224843 A224844 A224845 * A224847 A224848 A224849

Keyword

nonn

Author

Pierre CAMI, Jul 22 2013

Status

approved