39621

Appears in sequences

• A continued fraction.at n=12A001112
• Odd triangular numbers with prime indices.at n=28A034954
• Duplicate of A001112.at n=11A041299
• Numbers n such that 2^n - 21 is prime.at n=28A057202
• Triangular numbers with sum of digits = 21.at n=25A068131
• Triangle read by rows in which the n-th row contains the n smallest triangular numbers with the least significant digits of the n-th triangular number.at n=20A095225
• Diagonal of the triangle A095225.at n=5A095226
• Numbers k such that 2^k - 21 is prime.at n=24A096820
• Triangular numbers for which the sum of the digits is an octagonal number.at n=28A117523
• Triangular numbers t which are average of two consecutive primes p and p+4.at n=29A129752
• Triangular numbers t such that t+10 is a prime.at n=36A129755
• Hexagonal numbers (A000384) which are sum of 2 other hexagonal numbers > 0.at n=30A133215
• a(n) = m*(m+1)/2, where m = floor(n^(3/2)).at n=42A185541
• Triangular numbers which have one or more occurrences of exactly five different digits.at n=28A241788
• Irregular table read by rows: n-th row lists the 9 n-gonal numbers of a 3 X 3 semimagic square with the smallest magic sum. The terms of each row are arranged in the manner shown in A261816.at n=28A265141
• Triangular numbers that in base 2 have the same number of 0's and 1's.at n=23A345348
• Smallest number k in a set of three consecutive triangular numbers that are sphenic.at n=2A348185
• Smallest number m in a set of at least three consecutive triangular numbers with three distinct prime factors.at n=20A349539
• Smallest number in a set of three consecutive triangular numbers each with three prime factors (counted with multiplicity).at n=3A349696
• Hexagonal numbers that are sphenic numbers.at n=30A380007