A193732 Connell-like sequence.

1, 3, 4, 6, 8, 9, 11, 13, 15, 17, 18, 20, 22, 24, 26, 28, 30, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 110, 112, 114, 116, 118, 120

Offset

1,2

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Example

Let prime(n) denote the n-th prime.
Because prime(1)=2, take first 2 odd numbers giving a(1)=1, a(2)=3.
Because prime(2)=3, take 3 even numbers starting with 4 giving a(3)=4, a(4)=6, a(5)=8.
Because prime(3)=5, take 5 odd numbers starting with 9 giving a(6)=9, a(7)=11, a(8)=13, a(9)=15, a(10)=17.
Because prime(4)=7, take 7 even numbers starting with 18 gives a(11)=18, a(12)=20, ..., a(17)=30 etc.

Maple

cp:=2:ct:=1:a := proc(n) option remember: global cp, ct: if(n=1)then return 1: elif(ct=cp)then ct:=1:cp:=nextprime(cp): return a(n-1)+1: else ct:=ct+1: return a(n-1)+2: fi: end: seq(a(n), n=1..100); # Nathaniel Johnston, Aug 11 2011

Mathematica

nxt[{p_, a_}]:={NextPrime[p], Range[Last[a]+1, Last[a]+2*NextPrime[p], 2]}; Transpose[NestList[nxt, {2, {1, 3}}, 10]][[2]]//Flatten (* Harvey P. Dale, Mar 23 2016 *)

Crossrefs

Cf. A000040, A001614.

Sequence in context: A133280 A280762 A138097 * A000592 A138924 A188015

Adjacent sequences: A193729 A193730 A193731 * A193733 A193734 A193735

Keyword

nonn,easy

Author

Ctibor O. Zizka, Aug 08 2011

Status

approved