A138873 First two digits of n-th even perfect number.

6, 28, 49, 81, 33, 85, 13, 23, 26, 19, 13, 14, 23, 14, 54, 10, 99, 33, 18, 40, 11, 59, 39, 93, 10, 81, 36, 14, 13, 13, 27, 15, 83, 84, 33, 19, 81, 95, 42, 79, 44, 74, 49, 77, 20, 14, 50

Offset: 1

Author

Omar E. Pol, Apr 02 2008

Keywords

• base
• more
• nonn

Links

• Jan Munch Pedersen, Known Perfect Numbers [Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009]
• Omar E. Pol, Los numeros perfectos

Crossrefs

Cf. A000396, A138862, A138875.

First 2 digits of sequence A138875. [Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009]

Programs

Mathematica

Join[{6},FromDigits[Take[IntegerDigits[#],2]]&/@PerfectNumber[Range[2,50]]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 26 2020 *)

Extensions

a(15)-a(31) added by Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009

Definition changed (inserting the word "even") and a(37)-a(47) added by Ivan Panchenko, Aug 04 2018