A071598 a(0) = 1; a(n) = half of the a(n-1)-th even nontotient number.

1, 7, 34, 115, 298, 677, 1431, 2853, 5401, 9813, 17289, 29687, 49901, 82315, 133617, 213801, 337742, 527231, 814218, 1244962, 1886069, 2833392, 4223121, 6247850, 9179762, 13399951, 19440903, 28043882, 40233399, 57423953, 81557903

Offset: 0

Author

Robert G. Wilson v, Jun 20 2002

Keywords

• nonn

Examples

			a(5) = 677 = 1354/2, where 1354 is the a(4) = 298th term in A005277. [Corrected by _Sean A. Irvine_, Jul 28 2024]
		

Crossrefs

Cf. A005277, A072416.

Programs

Mathematica

a = Table[0, {10^6}]; Do[b = EulerPhi[n]/2; If[b < 10^6 + 1, a[[b]] = 1], {n, 1, 2 10^7}]; b = Select[ Range[10^6], a[[ # ]] == 0 &]; c = 1; Do[ Print[c]; c = b[[c]], {n, 0, 18}]

Extensions

a(19)-a(30) from Donovan Johnson, May 30 2010