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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). 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified September 26 16:43 EDT 2020. Contains 337374 sequences. (Running on oeis4.)