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A219677 Primes that generate 5 longer primes by prefacing their 5 successors in sequence. 1
3687530993, 4826397283, 7724657491, 9980308301, 15974564917, 28909417051, 75268578271, 80574464057, 93244706063, 99745568639, 103152269047, 142659491629, 154807590677 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This is similar to A219271, but the successor primes are here concatenated to the left rather than the right.

LINKS

Table of n, a(n) for n=1..13.

EXAMPLE

The primes following a(1)=3687530993 are 3687530999, 3687531007, 3687531011, 3687531019 and 3687531041, and each addition of these primes in sequence up through the final 60-digit 368753104136875310193687531011368753100736875309993687530993 yields a prime.

PROG

(PARI) [Output is a vector of 6 successive primes for each

element of the sequence, which is the smallest]

{

\\ This simple program checks modulo 3 first\\

p=[5, 7, 11, 13, 17, 19]; e=[10, 10, 100, 100, 100];

while(1,

if((p[1]+p[2])%3, f=1; for(i=2, 5,

if((p[i]+p[i+1])%3, f=0; break()));

if(f, P=p[1]+p[2]*e[1]; if(ispseudoprime(P),

E=e[1]; for(i=2, 5, E*=e[i]; P+=E*p[i+1];

if(ispseudoprime(P)==0, f=0; break()));

if(f, print(p)))));

for(i=1, 5, p[i]=p[i+1]); p[6]=nextprime(p[6]+1);

for(i=1, 4, e[i]=e[i+1]); if(p[5]>e[5], e[5]*=10))

}

CROSSREFS

Cf. A219271.

Sequence in context: A094722 A283458 A234433 * A061441 A135915 A104330

Adjacent sequences:  A219674 A219675 A219676 * A219678 A219679 A219680

KEYWORD

nonn,base

AUTHOR

James G. Merickel, Nov 25 2012

EXTENSIONS

Terms missing in original added by James G. Merickel, Jul 25 2013

STATUS

approved

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Last modified January 25 03:49 EST 2020. Contains 331241 sequences. (Running on oeis4.)