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A107806 a(1) = prime(6), for n >= 2, a(n) is the smallest prime not previously used which contains a digit from a(n-1). 14
13, 3, 23, 2, 29, 19, 11, 17, 7, 37, 31, 41, 43, 47, 67, 61, 71, 73, 53, 5, 59, 79, 89, 83, 103, 101, 107, 97, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = prime(n) for almost all n. Probably a(n) = prime(n) for all n > N for some N, but N must be very large. - Charles R Greathouse IV, Jul 20 2011

LINKS

Table of n, a(n) for n=1..59.

FORMULA

a(n) ~ n log n. - Charles R Greathouse IV, Jul 20 2011

MATHEMATICA

p=Prime[6]; b={p}; d=p; Do[Do[r=Prime[c]; If[FreeQ[b, r]&&Intersection@@IntegerDigits/@{d, r}=!={}, b=Append[b, r]; d=r; Break[]], {c, 1000}], {k, 60}]; b

PROG

(PARI) common(a, b)=a=vecsort(eval(Vec(Str(a))), , 8); b=vecsort(eval(Vec(Str(b))), , 8); #a+#b>#vecsort(concat(a, b), , 8)

in(v, x)=for(i=1, #v, if(v[i]==x, return(1))); 0

lista(nn) = {my(v=[13]); for(n=2, nn, forprime(p=2, default(primelimit), if(!in(v, p)&&common(v[#v], p), v=concat(v, p); break))); v; }

\\ Charles R Greathouse IV, Jul 20 2011

CROSSREFS

Cf. A107353.

Other cases of seed: A107801 (a(1) = 2), A107802 (a(1) = 3), A107803 (a(1) = 5), A107804 (a(1) = 7), A107805 (a(1) = 11), A107807 (a(1) = 17), A107808 (a(1) = 19), A107809 (a(1) = 23), A107810 (a(1) = 29), A107811 (a(1) = 31), A107812 (a(1) = 37), A107813 (a(1) = 41), A107814 (a(1) = 43).

Sequence in context: A128154 A213538 A264971 * A138965 A317313 A170922

Adjacent sequences:  A107803 A107804 A107805 * A107807 A107808 A107809

KEYWORD

nonn,base

AUTHOR

Zak Seidov & Eric Angelini, May 24 2005

STATUS

approved

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Last modified July 25 02:57 EDT 2021. Contains 346282 sequences. (Running on oeis4.)