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A033457 GCD-convolution of squares A000290 with themselves. 2
1, 2, 6, 4, 19, 6, 28, 24, 45, 10, 98, 12, 79, 94, 120, 16, 201, 18, 238, 164, 171, 22, 436, 120, 229, 234, 426, 28, 695, 30, 496, 352, 369, 370, 1014, 36, 451, 470, 1068, 40, 1261, 42, 946, 1020, 639, 46, 1832, 336 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Danny Rorabaugh, Table of n, a(n) for n = 0..10000

FORMULA

a(n-2) = Sum_{d|n, d<n} d^2*phi(n/d). - Vladeta Jovovic, Aug 27 2003

MATHEMATICA

Table[Sum[d^2*EulerPhi[(n + 2)/d], {d, Most@ Divisors[n + 2]}], {n, 0, 47}] (* Michael De Vlieger, Mar 20 2015 *)

PROG

(Sage) sum([d^2*euler_phi(int((n+2)/d)) for d in range(1, n+2) if (n+2)%d==0]) # Danny Rorabaugh, Mar 20 2015

CROSSREFS

Cf. A069097.

Sequence in context: A127320 A098917 A054786 * A133936 A065350 A063427

Adjacent sequences:  A033454 A033455 A033456 * A033458 A033459 A033460

KEYWORD

nonn,easy,changed

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified March 29 18:21 EDT 2015. Contains 256023 sequences.