A138866 Concatenation of first 3 digits and last 3 digits of n-th Mersenne prime A000668(n).

33, 77, 3131, 127127, 819191, 131071, 524287, 214647, 230951, 618111, 162127, 170727, 686151, 531127, 104087, 147007, 446351, 259071, 190991, 285607, 478111, 346551, 281191, 431471, 448751, 402511, 854671, 536207, 521007, 512311, 746447, 174887, 129591, 412527, 814711, 623151, 127271, 437791, 924071, 125047, 299407, 122247, 315871, 124871, 202927, 169751, 316511

Offset: 1

Author

Omar E. Pol, Apr 02 2008

Keywords

• base
• nonn

Links

• L. C. Noll, Mersenne Prime Digits and Names.

Crossrefs

Cf. A000668, A080173, A104511, A138816, A138817, A138840, A138841.

Programs

Mathematica

Join[{33,77,3131},FromDigits[Flatten[Join[{Take[IntegerDigits[#],3],Take[ IntegerDigits[ #],-3]}]]]&/@ (2^MersennePrimeExponent[Range[4,40]]-1)] (* Harvey P. Dale, Dec 30 2023 *)

Extensions

More terms from Harvey P. Dale, Dec 30 2023