A117531 Number of primes in the n-th row of the triangle in A117530.

1, 2, 3, 3, 5, 3, 7, 3, 5, 6, 6, 6, 13, 3, 11, 8, 12, 8, 13, 10, 8, 7, 12, 10, 9, 21, 6, 22, 11, 7, 13, 12, 21, 13, 14, 16, 18, 7, 20, 17, 21, 20, 24, 14, 18, 20, 16, 16, 35, 10, 18, 29, 18, 30, 30, 26, 21, 18, 21, 29, 16, 22, 32, 40, 10, 27, 24, 25, 45, 18, 39, 40, 43, 11, 11

Offset

1,2

Comments

1 <= a(n) <= n; conjecture: a(n) < n for n>13.

Links

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

Formula

a(n) = Sum_{k=1..n} A010051(A117530(n,k)).

Mathematica

Function[Count[#, _?PrimeQ]] /@ Table[k^2 - k + Prime[n], {n, 100}, {k, n}] (* Robert Price, Apr 19 2025 *)

Crossrefs

Cf. A010051, A117530.

Sequence in context: A111607 A327124 A329277 * A275940 A105555 A066858

Adjacent sequences: A117528 A117529 A117530 * A117532 A117533 A117534

Keyword

nonn

Author

Reinhard Zumkeller, Mar 25 2006

Status

approved