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A277804 Numbers n such that first digit of n divides n, last digit of n divides n, number of divisors of n divides n and phi(n) divides n, where phi(n) is the Euler totient function. 2
1, 2, 8, 12, 24, 36, 128, 288, 384, 864, 972, 1152, 1944, 3456, 6144, 6912, 13122, 18432, 26244, 31104, 62208, 69984, 209952, 279936, 294912, 497664, 839808, 884736, 1679616, 3538944, 4478976, 13436928, 22674816, 25165824, 31850496, 45349632 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Numbers n such that A000030(n)|n, A010879(n)|n, A000005(n)|n and A000010(n)|n.
Intersection of A007694, A034709, A033950 and A034837.
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..43
EXAMPLE
a(5) = 24 because 24/2 = 12, 24/4 = 6, 24 has 8 divisors {1,2,3,4,6,8,12,24}, 24/8 = 3, phi(24) = 8 {1,5,7,11,13,17,19,23} and 24/8 = 3 (all are an integers).
MATHEMATICA
Select[Range[50000000], Divisible[#1, First[IntegerDigits[#1]]] && Divisible[#1, Last[IntegerDigits[#1]]] && Divisible[#1, DivisorSigma[0, #1]] && Divisible[#1, EulerPhi[#1]] & ]
CROSSREFS
Sequence in context: A280252 A013654 A359964 * A108978 A269968 A135957
KEYWORD
nonn,base
AUTHOR
Ilya Gutkovskiy, Nov 01 2016
EXTENSIONS
a(24) - a(36) added by G. C. Greubel, Nov 02 2016
STATUS
approved

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Last modified March 28 15:28 EDT 2024. Contains 371254 sequences. (Running on oeis4.)