A330630 Palindromic composite numbers with palindromic composite indices (in A002808).

9, 77, 414, 545, 737, 818, 868, 5005, 9889, 24642, 45754, 87478, 974479, 1774771, 2735372, 4085804, 4549454, 4658564, 7673767, 8541458, 8671768, 9251529, 9478749, 9642469, 221131122, 425393524, 527111725, 554535455, 978909879, 7476336747, 8731001378, 15552425551

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..55

Example

The palindromic composite number 77 has palindromic composite index 55 in A002808. So 77 belongs to the present sequence.

Mathematica

composite[n_]:=FixedPoint[n+PrimePi[#]+1&, n+PrimePi[n]+1];
indices=Select[Range[10^6], CompositeQ[#]&&PalindromeQ[#]&&PalindromeQ[composite[#]]&];
terms=composite/@indices (*"composite" function defined by Robert G. Wilson v at A002808*)

Crossrefs

Cf. A002808, A002113.

Sequence in context: A209667 A276754 A075608 * A282327 A263471 A266125

Adjacent sequences: A330627 A330628 A330629 * A330631 A330632 A330633

Keyword

nonn,base,hard

Author

Ivan N. Ianakiev, Dec 21 2019

Extensions

a(1)-a(32) from Daniel Suteu, Dec 21 2019

Status

approved