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

Author

Reinhard Zumkeller, Mar 25 2006

Keywords

• nonn

Comments

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

Links

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

Crossrefs

Cf. A010051, A117530.

Programs

Mathematica

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

Formula

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