A181774 First differences of A181103.

1, 4, 6, 4, 2, 4, 6, 12, 6, 12, 24, 6, 12, 6, 30, 36, 6, 60, 12, 6, 12, 24, 18, 36, 42, 30, 30, 18, 90, 6, 36, 42, 6, 54, 60, 48, 18, 12, 18, 30, 60, 6, 18, 6, 42, 30, 42, 18, 42, 12, 54, 12, 30, 42, 66, 42, 78, 36, 36, 12, 36, 12, 48, 66, 54, 24, 66, 24, 6

Offset

1,2

Comments

For a(n) > 4, a(n) is divisible by 6.

Links

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

Formula

a(n) = A181103(n+1) - A181103(n).

Maple

A181103 := proc(n) option remember: local p: if(n<=2)then return n+1: fi: p:=procname(n-1): do p:=nextprime(p): if(isprime(abs(p-procname(n-2)-procname(n-1))))then return p: fi: od: end: seq(A181103(n+1)-A181103(n), n=1..69); # Nathaniel Johnston, May 27 2011

Mathematica

nxt[{a_, b_}]:=Module[{lp=NextPrime[b]}, While[!PrimeQ[Abs[a+b-lp]], lp = NextPrime[lp]]; {b, lp}]; Differences[NestList[nxt, {2, 3}, 70][[All, 1]]] (* Harvey P. Dale, Jul 26 2018 *)

Crossrefs

Sequence in context: A062751 A135911 A164356 * A291379 A001138 A133587

Adjacent sequences: A181771 A181772 A181773 * A181775 A181776 A181777

Keyword

nonn,easy

Author

Giovanni Teofilatto

Extensions

More terms from Giovanni Teofilatto

Status

approved