cp's OEIS Frontend

A369331 Positive numbers whose decimal expansions are covered by that of prime numbers (without leading zeros).

%I A369331 #4 Jan 24 2024 08:31:12
%S A369331 2,3,5,7,11,13,17,19,22,23,25,27,29,31,32,33,35,37,41,43,47,52,53,55,
%T A369331 57,59,61,67,71,72,73,75,77,79,83,89,97,101,103,107,109,111,112,113,
%U A369331 115,117,119,127,131,132,133,135,137,139,149,151,157,163,167,171
%N A369331 Positive numbers whose decimal expansions are covered by that of prime numbers (without leading zeros).
%C A369331 More formally: positive numbers with decimal expansion (d_1, ..., d_w) (where d_1 <> 0) such that for any i in 1..w, we have some j, k such that j <= i <= k and d_j <> 0 and (d_j, ..., d_k) corresponds to the decimal expansion of a prime number.
%C A369331 This sequence contains, among others, A000040, A046034 and A152242.
%C A369331 This sequence first differs from A152242 for n = 42: a(42) = 111 whereas A152242(42) = 112.
%H A369331 <a href="/index/De#decimal_expansion">Index entries for sequences related to decimal expansion of n</a>
%e A369331 The number 15195 belongs to the sequence for the following covering:
%e A369331        151
%e A369331          19
%e A369331            5
%e A369331        .....
%e A369331        15195
%o A369331 (PARI) is(n, base = 10) = { my (d = if (n, digits(n, base), [0]), ok = vector(#d), rem = #d); for (i = 1, #d, if (d[i], for (j = i, #d, if  (isprime( fromdigits( d[i..j], base)), for (k = i, j, if (ok[k]==0, ok[k]++; rem--; if (rem==0, return (1)))))))); return (0); }
%Y A369331 Cf. A000040, A046034, A152242.
%K A369331 nonn,base,easy
%O A369331 1,1
%A A369331 _Rémy Sigrist_, Jan 20 2024