A284412 a(1) = 1, a(2) = 2; a(n) is the largest prime <= (a(a(n-1)) + a(n-a(n-1))) for n > 2.

1, 2, 3, 3, 5, 5, 7, 7, 7, 7, 7, 11, 7, 13, 7, 13, 7, 13, 11, 13, 13, 13, 13, 13, 17, 13, 19, 17, 17, 13, 19, 17, 19, 17, 19, 17, 19, 19, 23, 19, 23, 23, 23, 23, 23, 23, 23, 29, 29, 29, 29, 29, 29, 31, 31, 31, 31, 37, 31, 31, 31, 37, 31, 37, 31, 37, 31, 37, 31, 41, 31, 41, 37, 37, 37, 41, 37, 41, 41, 43

Offset

1,2

Links

Altug Alkan, Table of n, a(n) for n = 1..10000

Altug Alkan, Scatterplot of n-2*a(n)

Altug Alkan, Plot of a(n)/n

Formula

a(1) = 1, a(2) = 2; a(n) = A007917(a(a(n-1)) + a(n-a(n-1))) for n > 2.

Example

a(6) = 5 because a(a(5)) + a(6 - a(5)) = a(5) + a(1) = 5 + 1 = 6 and A007917(6) = 5

Prog

(PARI) a=vector(1000); a[1]=1; a[2]=2; for(n=3, #a, a[n] = precprime(a[a[n-1]]+a[n-a[n-1]])); a

Crossrefs

Cf. A004001, A007917, A284374, A284383, A284397.

Sequence in context: A074399 A090302 A093074 * A136548 A007917 A151799

Adjacent sequences: A284409 A284410 A284411 * A284413 A284414 A284415

Keyword

nonn

Author

Altug Alkan, Mar 26 2017

Status

approved