A111034 Sum of squares of digits of e.

4, 53, 54, 118, 122, 186, 187, 251, 255, 319, 335, 360, 441, 441, 457, 482, 486, 495, 520, 529, 565, 565, 569, 633, 682, 698, 747, 748, 757, 782, 786, 822, 858, 862, 878, 959, 1008, 1057, 1082, 1131, 1135, 1151, 1200, 1200

Offset

1,1

Comments

a(n) is prime for n = 2, 8, 15, 23, 29, ... a(n) is semiprime for n = 1, 4, 5, 7, 10, 11, 16, 21, 22, 24, 26, ... a(n) is a perfect power for n = 1, 13, 14, 20, ... Coincidentally, a(20) = 529 = 23^2 = sum of squares of first 18 digits of pi.

Links

Table of n, a(n) for n=1..44.

Formula

a(n) = sum(i=1 to n) A001113(i)^2.

Example

a(1) = 2^2 = 4,
a(2) = 2^2 + 7^2 = 53, which is prime,
a(3) = 2^2 + 7^2 + 1^2 = 54,
a(4) = 2^2 + 7^2 + 1^2 + 8^2 = 118,
a(5) = 2^2 + 7^2 + 1^2 + 8^2 + 2^2 = 122.

Mathematica

Accumulate[RealDigits[E, 10, 50][[1]]^2]  (* Harvey P. Dale, Apr 05 2011 *)

Crossrefs

Cf. A001113.

Sequence in context: A193914 A288490 A219160 * A214367 A241872 A109801

Adjacent sequences: A111031 A111032 A111033 * A111035 A111036 A111037

Keyword

base,easy,nonn

Author

Jonathan Vos Post, Oct 05 2005

Extensions

More terms from Harvey P. Dale, Apr 05 2011.

Status

approved