A270815 Let M be the n-th Giuga number (see A007850); a(n) = sum of (M/p - 1)/p for primes p dividing M.

11, 321, 657, 24699, 824438641, 9331106993, 165242994898683, 5626813041698235, 210318566007979643, 90916134718317480897884289, 206287562744685037912181145873, 729990278282182004516138224533969

Offset

1,1

Comments

For the additional Giuga number (not known to be the next term of A007850), 4200017949707747062038711509670656632404195753751630609228764416142557211582098432545190323474818 the corresponding value is 1563694051115215735786664430977202618214176554388873529993304101116913223541171676954379378709457.

Links

Table of n, a(n) for n=1..12.

Example

Prime factors of 30 are 2, 3 and 5: (30/2 - 1)/2 + (30/3 - 1)/3 + (30/5 - 1)/5 = 7 + 3 + 1 = 11.

Maple

with(numtheory): P:=proc(q) local n, x; x:=[30, 858, 1722, 66198, 2214408306, 24423128562, 432749205173838, 14737133470010574, 550843391309130318, 244197000982499715087866346, 554079914617070801288578559178, 1910667181420507984555759916338506];
for n from 1 to nops(x) do print(add((x[n]/k-1)/k, k=factorset(x[n]))); od; end: P(1);

Crossrefs

Cf. A007850, A270816.

Sequence in context: A166053 A200749 A324422 * A197448 A241127 A268551

Adjacent sequences: A270812 A270813 A270814 * A270816 A270817 A270818

Keyword

nonn,more

Author

Paolo P. Lava, Mar 23 2016

Status

approved