The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A144006 Triangle, read by rows of coefficients of x^n*y^k for k=0..n(n-1)/2 for n>=0, defined by e.g.f.: A(x,y) = 1 + Series_Reversion( Integral A(-x*y,y) dx ), with leading zeros in each row suppressed. 1
 1, 1, 1, 3, -1, 15, -10, 3, -1, 105, -105, 55, -30, 10, -3, 1, 945, -1260, 910, -630, 350, -168, 76, -30, 10, -3, 1, 10395, -17325, 15750, -12880, 9135, -5789, 3381, -1806, 910, -434, 196, -76, 30, -10, 3, -1, 135135, -270270, 294525, -275275, 228375 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS FORMULA E.g.f. satisfies: A(x,y) = 1 + Series_Reversion[Integral A(-x*y,y) dx]. T(n,k) = [x^n*y^k] n!*A(x,y) for k=0..n(n-1)/2, n>=0. Row sums equal A144005. A067146(n) = Sum_{k=0..n(n-1)/2} (-1)^k*T(n,k). Conjectured to be a signed version of table A014621. Conjecture: row sums form A014623. Conjecture: unsigned row sums form A014622. EXAMPLE Triangle begins (without suppressing leading zeros): 1; 1; 0, 1; 0,0, 3, -1; 0,0,0, 15, -10, 3, -1; 0,0,0,0, 105, -105, 55, -30, 10, -3, 1; 0,0,0,0,0, 945, -1260, 910, -630, 350, -168, 76, -30, 10, -3, 1; 0,0,0,0,0,0, 10395, -17325, 15750, -12880, 9135, -5789, 3381, -1806, 910, -434, 196, -76, 30, -10, 3, -1; 0,0,0,0,0,0,0, 135135, -270270, 294525, -275275, 228375, -172200, 120960, -78519, 48006, -28336, 16065, -8609, 4461, -2166, 1018, -470, 196, -76, 30, -10, 3, -1; ... PROG (PARI) {T(n, k)=local(A=1+x*O(x^n)); for(i=0, n, A=1+serreverse(intformal(subst(A, x, -x*y)))); n!*polcoeff(polcoeff(A, n, x), k, y)} CROSSREFS Cf. A144005, A067146. Conjectured to generate A014621, A014622 and A014623, which are related to Levine's sequence A011784. Sequence in context: A130757 A181996 A014621 * A193966 A113378 A178657 Adjacent sequences:  A144003 A144004 A144005 * A144007 A144008 A144009 KEYWORD sign,tabf AUTHOR Paul D. Hanna, Sep 10 2008 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 28 16:42 EST 2021. Contains 349413 sequences. (Running on oeis4.)