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A285710 Numbers n for which A000010(n) = A285699(n); positions of zeros in A285709. 6
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 (list; graph; refs; listen; history; text; internal format)
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(list(filter(lambda i: core(i) == i, divisors(n))))

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 xrange(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: A129562 A191841 A050741 * A133810 A176615 A291453

Adjacent sequences:  A285707 A285708 A285709 * A285711 A285712 A285713

KEYWORD

nonn

AUTHOR

Antti Karttunen, Apr 26 2017

STATUS

approved

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Last modified November 23 19:08 EST 2017. Contains 295128 sequences.