A181659 Numbers at which the sum of the iterated totient function (A092693) attains a record.

1, 2, 3, 5, 7, 11, 13, 17, 23, 29, 37, 41, 47, 53, 59, 71, 73, 79, 83, 89, 101, 107, 131, 137, 167, 179, 227, 233, 257, 289, 317, 347, 359, 389, 443, 449, 461, 467, 503, 557, 563, 569, 587, 641, 719, 809, 839, 857, 929, 977, 983, 1013, 1019, 1097, 1187, 1193, 1283

Offset

1,2

Comments

Most of these numbers are prime. The first four composites are 289, 2329, 4369, and 4913.

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Mathematica

kMax=2*3*5*7*11*13; t=Table[0, {kMax}]; Do[e=EulerPhi[k]; t[[k]]=e+t[[e]], {k, 2, kMax}]; mx=-1; Reap[Do[If[t[[k]]>mx, mx=t[[k]]; Sow[k]], {k, kMax}]][[2, 1]]

Crossrefs

Cf. A181660

Cf. A126106 (record values)

Sequence in context: A368732 A192503 A040067 * A040087 A040065 A051647

Adjacent sequences: A181656 A181657 A181658 * A181660 A181661 A181662

Keyword

nonn

Author

T. D. Noe, Nov 04 2010

Status

approved