A143391 A binomial recursion sequence: a(n+1) = binomial(a(n),n), with a(1) = 4.

4, 4, 6, 20, 4845, 22201944189472719, 166346452361171550314824489703019621783015631944522524541726975745905615181160551330988078433117

Offset

1,1

Comments

a(8) is:

699301187738697776955234590818575878858497870436943950335371702267592105356658

849941404678768037675247402565958747959976067293704659262352355225014691708927

778552892641086343071274181444416049073520682688565978919033071721714880653653

080309872598715536025092978123435527211585005389271350498723935289464449420805

795571832413526658955115512510611494293919617563498533091225832128243546205605

992399467856781652450135524637534848361445349052823349129955310671992962375769

922037205735947982909072338647248893042158639365515004077074834659222711212403

575797324146436716175464082981330742529857175516323162599993277609188166949854

918220220568926227236394740277576705068

The sequence continues to grow quite rapidly thereafter.

a(1) = 4 is the smallest meaningful seed for the sequence; if we start with a(1) = 3, the sequence is finite: 3,3,1.

Links

Table of n, a(n) for n=1..7.

Mathematica

a[1] = 4; a[n_] := a[n] = Binomial[a[n - 1], n - 1];
Table[a[n], {n, 1, 8}]

Crossrefs

Sequence in context: A352845 A128089 A019176 * A158661 A264578 A261146

Adjacent sequences: A143388 A143389 A143390 * A143392 A143393 A143394

Keyword

nonn

Author

Roger L. Bagula and Gary W. Adamson, Oct 23 2008

Extensions

Edited by Franklin T. Adams-Watters, Oct 05 2017

Status

approved