A089182 Prime digit palindromes 2,...,23577532 continued by adding 10^(n-k) and 10^(k-1) times prime(k).

2, 22, 232, 2332, 23532, 235532, 2357532, 23577532, 235817532, 2358217532, 23582417532, 235824417532, 2358248417532, 23582488417532, 235824908417532, 2358249108417532, 23582491508417532, 235824915508417532

Offset: 1

Author

Roger L. Bagula, Dec 07 2003

Keywords

• nonn
• base

Comments

Original definition: Overlapping prime-based palindromic sequence.

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.

Crossrefs

Cf. A007907, A138140.

Programs

Mathematica

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}]

Formula

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

Extensions

Edited by M. F. Hasler, Apr 06 2009