cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A051862 Perturbation expansion in quantum field theory: scalar case in 6 spacetime dimensions.

Original entry on oeis.org

0, 1, 11, 376, 20241, 1427156, 121639250, 12007003824, 1337583507153, 165328009728652, 22404009743110566, 3299256277254713760, 524366465815117346250, 89448728780073829991976, 16301356287284530869810308, 3161258841758986060906197536, 650090787950164885954804021185
Offset: 0

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Author

David Broadhurst, Dec 14 1999

Keywords

Examples

			a(31) = 7632236320181399967333968684399053053157812979126909028545984868160 was computed using Kreimer's Hopf algebra of rooted trees. It subsumes 2.6*10^21 terms in quantum field theory.
		

Crossrefs

Cf. A000699.

Programs

  • Sage
    t = PowerSeriesRing(QQ, 't').gen()
    def shadok(c):
        """
        fixed point procedure after G. Dunne talk at Kreimer's fest 2020
        """
        aa_sur_c = 2 * t * c.derivative() - c - 3
        aa = c * aa_sur_c
        bb_sur_c = 2 * t * aa.derivative() - aa - 2 * aa_sur_c
        bb = c * bb_sur_c
        cc_sur_c = 2 * t * bb.derivative() - bb - bb_sur_c
        return 3 * t / cc_sur_c
    C = (-t / 2).O(2)
    for k in range(10):
        C = shadok(C)
    list(1 / 6 * C(-12 * t))
    # F. Chapoton, Nov 19 2020

Formula

The generating procedure is described by Broadhurst and Kreimer.

Extensions

a(0)=0 and more terms from F. Chapoton, Nov 19 2020