A285710 Numbers n for which A000010(n) = A285699(n); positions of zeros in A285709.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 14, 16, 17, 19, 21, 23, 25, 27, 28, 29, 31, 32, 37, 41, 43, 47, 49, 53, 59, 61, 62, 64, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 121, 124, 125, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 237

Offset

1,2

Comments

After a(1) = 1, also numbers n such that A051953(n) = A079277(n).

Links

Antti Karttunen, Table of n, a(n) for n = 1..6672

Mathematica

Flatten@ Position[#, 0] &@ Table[EulerPhi@ n - (n - If[n <= 2, n - 1, Module[{k = n - 2, e = Floor@ Log2@ n}, While[PowerMod[n, e, k] != 0, k--]; k]]), {n, 240}] (* Michael De Vlieger, Apr 26 2017 *)

Prog

(Scheme, with Antti Karttunen's IntSeq-library)
(define A285710 (ZERO-POS 1 1 A285709))
(Python)
from sympy import divisors, totient
from sympy.ntheory.factor_ import core
def a007947(n): return max(i for i in divisors(n) if core(i) == i)
def a079277(n):
    k=n - 1
    while True:
        if a007947(k*n) == a007947(n): return k
        else: k-=1
def a285699(n): return 1 if n<2 else n - a079277(n)
print([n for n in range(1, 301) if totient(n) == a285699(n)]) # Indranil Ghosh, Apr 26 2017

Crossrefs

Positions of zeros in A285709.

Cf. A000010, A051953, A079277, A208815, A285699.

Cf. A000961 (a subsequence).

Sequence in context: A331125 A318736 A050741 * A305669 A325364 A133810

Adjacent sequences: A285707 A285708 A285709 * A285711 A285712 A285713

Keyword

nonn

Author

Antti Karttunen, Apr 26 2017

Status

approved