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A264441 Length of row n of the irregular triangle A133995 (positive integers <= n which are neither divisors of n nor coprime to n). 2
1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 5, 4, 4, 1, 7, 1, 7, 6, 9, 1, 9, 3, 11, 6, 11, 1, 15, 1, 11, 10, 15, 8, 16, 1, 17, 12, 17, 1, 23, 1, 19, 16, 21, 1, 23, 5, 25, 16, 23, 1, 29, 12, 25, 18, 27, 1, 33, 1, 29, 22, 26, 14, 39, 1, 31, 22, 39, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,10

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

FORMULA

a(1) = 1, a(4) = 1 and a(n) = 1 if n is a prime (n from A000040) else a(n) = A045763(n).

a(n) = max(1, A045763(n)). - Robert Israel, Jan 28 2016

MAPLE

seq(max(1, n - numtheory:-tau(n) - numtheory:-phi(n) + 1), n=1..100); # Robert Israel, Jan 28 2016

MATHEMATICA

a[1] = a[4] = 1; a[n_] := If[PrimeQ[n], 1, n + 1 - DivisorSigma[0, n] - EulerPhi[n]]; Array[a, 100] (* Jean-Fran├žois Alcover, Jan 18 2016 *)

PROG

(PARI) A264441(n) = max(1, n+1-numdiv(n)-eulerphi(n)); \\ Antti Karttunen, Mar 04 2018, after code in A045763.

CROSSREFS

Cf. A000040, A045763,  A133995.

Sequence in context: A322436 A013603 A157892 * A328573 A283461 A146907

Adjacent sequences:  A264438 A264439 A264440 * A264442 A264443 A264444

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, Jan 16 2016

STATUS

approved

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Last modified October 20 22:44 EDT 2019. Contains 328291 sequences. (Running on oeis4.)