A115062 Prime nearest to 10^n. In case of a tie, choose the smaller.

2, 11, 101, 997, 10007, 100003, 1000003, 9999991, 100000007, 1000000007, 10000000019, 100000000003, 999999999989, 9999999999971, 99999999999973, 999999999999989, 10000000000000061, 99999999999999997, 1000000000000000003, 9999999999999999961

Offset

0,1

Links

Alois P. Heinz, Table of n, a(n) for n = 0..300

Formula

a(n) = 10^n + A117190(n).

Maple

a:= n-> (t->((p, q)->`if`(q-t<t-p, q, p))(`if`(t=1, -1,
        prevprime(t)), nextprime(t)))(10^n):
seq(a(n), n=0..25);  # Alois P. Heinz, Aug 13 2014

Mathematica

Table[Min[Nearest[{NextPrime[10^n], NextPrime[10^n, -1]}, 10^n]], {n, 0, 20}] (* Harvey P. Dale, Mar 14 2023 *)

Prog

(PARI) for(n=0, 20, a=10^n-precprime(10^n); b=nextprime(10^n)-10^n; if(a<=b && n!=0, print1(precprime(10^n), ", "), print1(nextprime(10^n), ", "))) \\ Felix Fröhlich, Aug 13 2014

Crossrefs

Cf. A003617, A003618, A117190.

Sequence in context: A036953 A368879 A254320 * A062397 A158578 A003617

Adjacent sequences: A115059 A115060 A115061 * A115063 A115064 A115065

Keyword

nonn

Author

Lekraj Beedassy, Mar 01 2006

Extensions

More terms from Giovanni Resta and Rick L. Shepherd, Mar 01 2006

Status

approved