login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A345945
Numbers k that have such a proper divisor d for which A002034(d) = A002034(k).
4
6, 8, 10, 12, 14, 15, 18, 20, 21, 22, 24, 26, 28, 30, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 114, 115, 116, 117
OFFSET
1,1
EXAMPLE
21 = 3*7 is present because A002034(21) = 7 = A002034(7).
PROG
(PARI)
A002034(n) = if(1==n, n, my(s=factor(n)[, 1], k=s[#s], f=Mod(k!, n)); while(f, f*=k++); (k)); \\ After code in A002034.
A345950(n) = { my(x=A002034(n)); fordiv(n, d, if(A002034(d)==x, return(d==n))); };
isA345945(n) = !A345950(n);
CROSSREFS
Cf. A002034, A345944 (complement).
Positions of terms > 1 in A345935.
Union of A024619 and A345946.
Cf. also A344882.
Sequence in context: A268388 A139118 A089229 * A123240 A131181 A064176
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 04 2021
STATUS
approved