A073176 First n-digit prime in the concatenation of odd integers allowing leading zeros.

3, 13, 911, 5791, 79111, 31051, 1232527, 23252729, 113151719, 2527293133, 57911131517, 991011031051, 6769717375777, 13579111315171, 135791113151719, 4547495153555759, 31517192123252729, 719212325272931333, 1131517192123252729, 71921232527293133353

Offset

1,1

Comments

Leading zeros count but are not printed (cf. A073428).

Links

Robert Israel, Table of n, a(n) for n = 1..996

Example

a(4) = 5791 because first 4-digit prime in 135791113151719212325272931333537394143454749... is 5791. Notice that a(6) = 31051 because actually it is 031051, If we remove initial zeros, then a(6) = 105107.

Maple

S:= "":
for i from 1 to 300 by 2 do
  S:= cat(S, sprintf("%d", i))
od:
nS:= length(S):
for n from 1 do
  found:= false;
  for i from 1 to nS-n+1 do
    x:= parse(S[i..n+i-1]);
    if isprime(x) then R[n]:= x; found:= true; break fi
  od;
  if not found then break fi;
od:
seq(R[i], i=1..n-1); # Robert Israel, Nov 27 2024

Crossrefs

Cf. A005408, A073062, A073175, A073428.

Sequence in context: A368297 A065831 A092540 * A073428 A118628 A112513

Adjacent sequences: A073173 A073174 A073175 * A073177 A073178 A073179

Keyword

easy,nonn,base

Author

Zak Seidov, Aug 22 2002

Extensions

Data corrected by Sean A. Irvine, Nov 20 2024

Name modified by Sean A. Irvine, Jan 31 2025

Status

approved