A089182 - OEIS

A089182

Prime digit palindromes 2,...,23577532 continued by adding 10^(n-k) and 10^(k-1) times prime(k).

%I #15 Jul 22 2020 11:41:15

%S 2,22,232,2332,23532,235532,2357532,23577532,235817532,2358217532,

%T 23582417532,235824417532,2358248417532,23582488417532,

%U 235824908417532,2358249108417532,23582491508417532,235824915508417532

%N Prime digit palindromes 2,...,23577532 continued by adding 10^(n-k) and 10^(k-1) times prime(k).

%C Original definition: Overlapping prime-based palindromic sequence.

%C Only the first 8 terms are truly palindromes: a modulo 10 version of this would work with a limited digit set {1,2,3,5,7,9} with 2 and 5 only occurring as 1st and 3rd digit to either side.

%F a(n) = Sum_{k=1..floor(n/2)} prime(k)*(10^(n-k) + 10^(k-1)) + (n mod 2)*prime((n+1)/2)*10^floor(n/2). - _M. F. Hasler_, Apr 06 2009

%t a[m_]=Delete[Table[If [ Floor[m/2]-n>=0, Prime[ n], Prime[m-n]], {n, 1, m}], m] b=Table[Sum[a[m][[i]]*10^(i-1), {i, 1, m-1}], {m, 2, digits}]

%Y Cf. A007907, A138140.

%K nonn,base

%O 1,1

%A _Roger L. Bagula_, Dec 07 2003

%E Edited by _M. F. Hasler_, Apr 06 2009