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

1,1

Links

Table of n, a(n) for n=1..47.

Jan Munch Pedersen, Known Perfect Numbers [Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009]

Omar E. Pol, Los numeros perfectos

Mathematica

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

Crossrefs

Cf. A000396, A138862, A138875.

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

Sequence in context: A055196 A323752 A120624 * A091307 A254879 A298168

Adjacent sequences: A138870 A138871 A138872 * A138874 A138875 A138876

Keyword

base,more,nonn

Author

Omar E. Pol, Apr 02 2008

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

Status

approved