42486

Appears in sequences

• a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (1, p(1), p(2), ...).at n=36A024479
• a(n) is the smallest m for which the decimal representation of 2^m contains n consecutive identical digits.at n=9A045875
• Numbers k such that 12^k == -1 (mod k-1).at n=4A055695
• Squarefree n such that the elliptic curve n*y^2 = x^3 - x arising in the "congruent number" problem has rank 3 and nontrivial SHA[2].at n=0A062694
• Triangular numbers whose sum of squared digits is also triangular.at n=20A094890
• Triangular numbers with only even digits.at n=11A117978
• Exponent of least power of 2 having exactly n consecutive 9's in its decimal representation.at n=10A131543
• Hexagonal numbers (A000384) which are sum of 2 other hexagonal numbers > 0.at n=32A133215
• a(n) = m*(m+1)/2, where m = floor(n^(3/2)).at n=43A185541
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 137", based on the 5-celled von Neumann neighborhood.at n=42A270276
• Triangular numbers that are palindromes in base 9.at n=14A350993
• Hexagonal numbers that are products of exactly four distinct primes.at n=23A381920