A072206 Third terms of triple Peano sequence A071988.

2, 4, 15, 42, 176, 299, 697, 988, 1794, 3683, 4526, 7807, 10701, 12384, 16262, 23479, 32568, 36051, 47972, 57226, 62269, 79158, 91964, 113653, 147537, 166751, 176954, 198592, 210043, 234249, 333502, 366276, 419357, 438128, 540423, 562626, 632867

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

Numbers, except 2, satisfy a(n) = 1 + k/3 * (4k^2+5), with k in A005097. - Ralf Stephan, Aug 21 2004

a(n) = (n^3+5*n+6)/6, for n+1 prime, so a(n) = A000125(A006093(n)) - Bert Seghers, Jan 01 2012, corrected by Robert Israel, Jun 20 2019

Maple

g:= n -> (n^3+5*n+6)/6:
seq(g(ithprime(i)-1), i=1..100); # Robert Israel, Jun 20 2019

Mathematica

seq[n_Integer?Positive] := Module[{fn01 = 1, fn10 = 1, fnout = 1}, Do[{fn10, fn01, fnout} = {fn10 + 1, fn01 + fn10, fn01 + fnout}, {n - 1}]; {fn10, fn01, fnout}]; Ar = Flatten[ Table[ seq[ Prime[n]], {n, 1, 50}]]; a = {}; Do[a = Append[a, Ar[[n]]], {n, 3, 150, 3}]; a

Crossrefs

Cf. A000125, A006093, A071988.

Sequence in context: A148278 A284728 A187928 * A296255 A277508 A332234

Adjacent sequences: A072203 A072204 A072205 * A072207 A072208 A072209

Keyword

nonn

Author

Robert G. Wilson v, Jul 03 2002

Status

approved