The On-Line Encyclopedia of Integer Sequences (OEIS)

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Revision History for A368697

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Numbers that are divisible by the squares of two distinct primes and whose arithmetic derivative (A003415) is a squarefree number of the form 4k+2.
(history; published version)

#4 by Michael De Vlieger at Tue Jan 09 16:56:31 EST 2024

STATUS

proposed

approved

#3 by Antti Karttunen at Tue Jan 09 15:10:50 EST 2024

STATUS

editing

proposed

#2 by Antti Karttunen at Tue Jan 09 09:52:56 EST 2024

NAME

allocated for Antti KarttunenNumbers that are divisible by the squares of two distinct primes and whose arithmetic derivative (A003415) is a squarefree number of the form 4k+2.

DATA

11025, 17325, 27225, 28665, 29925, 36225, 37485, 38025, 40425, 47025, 48825, 49725, 53361, 56925, 63525, 63945, 65025, 69825, 70785, 74025, 74529, 76725, 81225, 81585, 84525, 84825, 88725, 90405, 92169, 92565, 92925, 98325, 105525, 106425, 108225, 110925, 111573, 111825, 113925, 116325, 116865, 117117, 119025, 119925

OFFSET

1,1

PROG

(PARI)

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));

A057521(n) = { my(f=factor(n)); prod(i=1, #f~, if(f[i, 2]>1, f[i, 1]^f[i, 2], 1)); };

isA368697(n) = if(omega(A057521(n))<2, 0, my(d=A003415(n)); ((2==(d%4))&&issquarefree(d)));

CROSSREFS

Intersection of A036785 and A368696, i.e., of A036785, A327862 and A328393.

Cf. A003415, A057521.

KEYWORD

allocated

nonn

AUTHOR

Antti Karttunen, Jan 09 2024

STATUS

approved

editing

#1 by Antti Karttunen at Wed Jan 03 14:48:51 EST 2024

NAME

allocated for Antti Karttunen

KEYWORD

allocated

STATUS

approved