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A111054 Sum of squares of digits of decimal expansion of square root of 2. 0

%I

%S 1,17,18,34,38,39,48,73,109,113,122,171,180,180,261,286,286,302,366,

%T 430,430,431,467,531,595,644,648,664,668,668,749,785,866,930,930,979,

%U 1043,1068,1104,1185,1221,1270,1271,1335,1384,1409,1418,1467,1503,1584

%N Sum of squares of digits of decimal expansion of square root of 2.

%C a(n) is prime for n = 2, 8, 9, 10, 22, 23, 46, ... a(n) is semiprime for n = 4, 5, 6, 11, 18, 31, 32, 33, 36, 37, 43, 47, ... a(n) is a perfect power for n = 1, 4, ...

%F a(n) = sum(i=1 to n) A002193(i)^2.

%e a(1) = 1^2 = 1,

%e a(2) = 1^2 + 4^2 = 17, which is prime,

%e a(3) = 1^2 + 4^2 + 1^2 = 18,

%e a(4) = 1^2 + 4^2 + 1^2 + 4^2 = 36,

%e a(10) = 1^2 + 4^2 + 1^2 + 4^2 + 2^2 + 1^2 + 3^2 + 5^2 + 6^2 + 2^2 = 113, which is prime.

%Y Cf. A002193, A111033, A111034.

%K base,easy,nonn

%O 1,2

%A _Jonathan Vos Post_, Oct 06 2005

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Last modified June 20 17:43 EDT 2021. Contains 345199 sequences. (Running on oeis4.)