A375020 Alternating sum phi(1) - phi(2) + phi(3) - phi(4) + ... + ((-1)^(10^n+1))*phi(10^n).

1, 6, 970, 101130, 10129180, 1013176996, 101320714074, 10132113873280, 1013211797886962, 101321183436796684, 10132118360452306248, 1013211836390484051818, 101321183641942857932324, 10132118364229503528908162, 1013211836423347845936784704

Offset: 0

Author

Chai Wah Wu, Aug 04 2024

Keywords

• nonn

Comments

Digits of terms converge towards 1/Pi^2 = 0.1013211836423...

Crossrefs

Cf. A002088, A049690, A068773.

Programs

Python

# uses code from A002088 and A049690
def A375020(n): return A002088(10**n)-(A049690(10**n>>1)<<1)

Formula

a(n) = A068773(10^n).