freeCodeCamp/problem-167-investigating-ulam-sequences.english.md at 908adc2c372f2c1af0c8d1c80b264c23f96fd7d7

mrugesh 22afc2a0ca feat(learn): python certification projects (#38216 )

Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Co-authored-by: Kristofer Koishigawa <scissorsneedfoodtoo@gmail.com>
Co-authored-by: Beau Carnes <beaucarnes@gmail.com>

2020-05-27 13:19:08 +05:30

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id, challengeType, isHidden, title, forumTopicId

id	challengeType	isHidden	title	forumTopicId
5900f4141000cf542c50ff26	5	false	Problem 167: Investigating Ulam sequences	301801

Description

For two positive integers a and b, the Ulam sequence U(a,b) is defined by U(a,b)1 = a, U(a,b)2 = b and for k > 2, U(a,b)k is the smallest integer greater than U(a,b)(k-1) which can be written in exactly one way as the sum of two distinct previous members of U(a,b). For example, the sequence U(1,2) begins with 1, 2, 3 = 1 + 2, 4 = 1 + 3, 6 = 2 + 4, 8 = 2 + 6, 11 = 3 + 8; 5 does not belong to it because 5 = 1 + 4 = 2 + 3 has two representations as the sum of two previous members, likewise 7 = 1 + 6 = 3 + 4. Find ∑U(2,2n+1)k for 2 ≤ n ≤10, where k = 1011.

Instructions

Tests

tests:
  - text: <code>euler167()</code> should return 3916160068885.
    testString: assert.strictEqual(euler167(), 3916160068885);

Challenge Seed

function euler167() {
  // Good luck!
  return true;
}

euler167();

Solution

// solution required

1.2 KiB Raw Blame History