A201156 Row sums of triangle A201146.

1, 3, 10, 11, 56, 57, 400, 401, 402, 403, 4434, 4435, 57656, 57657, 57658, 57659, 980204, 980205, 18623896, 18623897, 18623898, 18623899, 428349678, 428349679, 428349680, 428349681, 428349682, 428349683, 12422140808, 12422140809, 385086365080, 385086365081

Offset

1,2

Comments

a(n) = a(n-1) + 1 if and only if n is a composite number.

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..502

Mathematica

Table[Sum[Product[Prime[i], {i, PrimePi[n]}]/Product[Prime[i], {i, PrimePi[k]}], {k, n}], {n, 32}]

Crossrefs

Cf. A201146.

Sequence in context: A119221 A119219 A125569 * A309525 A253807 A212993

Adjacent sequences: A201153 A201154 A201155 * A201157 A201158 A201159

Keyword

nonn

Author

Arkadiusz Wesolowski, Nov 27 2011

Status

approved