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A286361 Least number with the same prime signature as {the largest divisor of n with only prime factors of the form 4k+1} has: a(n) = A046523(A170818(n)). 8
1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 1, 1, 1, 4, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 2, 1, 2, 2, 2, 1, 1, 1, 2, 1, 1, 1, 1, 4, 2, 2, 2, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 1, 6, 1, 1, 2, 1, 2, 1, 1, 2, 2, 4, 1, 1, 2, 1, 2, 1, 2, 1, 1, 6, 1, 2, 1, 2, 2, 2, 1, 1, 1, 2, 1, 2, 1, 1, 4, 2, 2, 1, 2, 2, 2, 1, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A046523(A170818(n)).

a(n) = A286363(A267099(n)).

PROG

(Scheme) (define (A286361 n) (A046523 (A170818 n)))

(Python)

from sympy import factorint

from operator import mul

def P(n):

    f = factorint(n)

    return sorted([f[i] for i in f])

def a046523(n):

    x=1

    while True:

        if P(n) == P(x): return x

        else: x+=1

def a072438(n):

    f = factorint(n)

    return 1 if n == 1 else reduce(mul, [1 if i%4==1 else i**f[i] for i in f])

def a(n): return a046523(n/a072438(n)) # Indranil Ghosh, May 09 2017

CROSSREFS

Cf. A046523, A170818, A267099, A267113, A286363, A286364, A286365.

Differs from A063014 for the first time at n=25, where a(25) = 4, while A063014(25) = 3.

Sequence in context: A157196 A293451 A063014 * A097295 A220572 A083896

Adjacent sequences:  A286358 A286359 A286360 * A286362 A286363 A286364

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 08 2017

STATUS

approved

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Last modified December 13 01:33 EST 2017. Contains 295954 sequences.