137550
domain: N
Appears in sequences
- Triangular numbers that are sandwiched between two semiprimes; or triangular numbers t such that t-1 and t+1 are both semiprime.at n=25A121898
- Triangular numbers that are sandwiched between two squarefree semiprimes.at n=23A375384
- Expansion of e.g.f. (1/x) * Series_Reversion( x/(1 + (exp(x^2) - 1)/x) ).at n=7A392889